UITextView 中的占位符
-
19-09-2019 - |
题
我的应用程序使用 UITextView
. 。现在我想要 UITextView
拥有一个类似于您可以为 UITextField
.
这个怎么做?
解决方案
我做了一些小的修改BCD的解决方案,以允许从Xib
文件,文本换行初始化,并保持背景颜色。希望这将节省别人的麻烦。
<强> UIPlaceHolderTextView.h:强>
#import <Foundation/Foundation.h>
IB_DESIGNABLE
@interface UIPlaceHolderTextView : UITextView
@property (nonatomic, retain) IBInspectable NSString *placeholder;
@property (nonatomic, retain) IBInspectable UIColor *placeholderColor;
-(void)textChanged:(NSNotification*)notification;
@end
<强> UIPlaceHolderTextView.m:强>
#import "UIPlaceHolderTextView.h"
@interface UIPlaceHolderTextView ()
@property (nonatomic, retain) UILabel *placeHolderLabel;
@end
@implementation UIPlaceHolderTextView
CGFloat const UI_PLACEHOLDER_TEXT_CHANGED_ANIMATION_DURATION = 0.25;
- (void)dealloc
{
[[NSNotificationCenter defaultCenter] removeObserver:self];
#if __has_feature(objc_arc)
#else
[_placeHolderLabel release]; _placeHolderLabel = nil;
[_placeholderColor release]; _placeholderColor = nil;
[_placeholder release]; _placeholder = nil;
[super dealloc];
#endif
}
- (void)awakeFromNib
{
[super awakeFromNib];
// Use Interface Builder User Defined Runtime Attributes to set
// placeholder and placeholderColor in Interface Builder.
if (!self.placeholder) {
[self setPlaceholder:@""];
}
if (!self.placeholderColor) {
[self setPlaceholderColor:[UIColor lightGrayColor]];
}
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(textChanged:) name:UITextViewTextDidChangeNotification object:nil];
}
- (id)initWithFrame:(CGRect)frame
{
if( (self = [super initWithFrame:frame]) )
{
[self setPlaceholder:@""];
[self setPlaceholderColor:[UIColor lightGrayColor]];
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(textChanged:) name:UITextViewTextDidChangeNotification object:nil];
}
return self;
}
- (void)textChanged:(NSNotification *)notification
{
if([[self placeholder] length] == 0)
{
return;
}
[UIView animateWithDuration:UI_PLACEHOLDER_TEXT_CHANGED_ANIMATION_DURATION animations:^{
if([[self text] length] == 0)
{
[[self viewWithTag:999] setAlpha:1];
}
else
{
[[self viewWithTag:999] setAlpha:0];
}
}];
}
- (void)setText:(NSString *)text {
[super setText:text];
[self textChanged:nil];
}
- (void)drawRect:(CGRect)rect
{
if( [[self placeholder] length] > 0 )
{
if (_placeHolderLabel == nil )
{
_placeHolderLabel = [[UILabel alloc] initWithFrame:CGRectMake(8,8,self.bounds.size.width - 16,0)];
_placeHolderLabel.lineBreakMode = NSLineBreakByWordWrapping;
_placeHolderLabel.numberOfLines = 0;
_placeHolderLabel.font = self.font;
_placeHolderLabel.backgroundColor = [UIColor clearColor];
_placeHolderLabel.textColor = self.placeholderColor;
_placeHolderLabel.alpha = 0;
_placeHolderLabel.tag = 999;
[self addSubview:_placeHolderLabel];
}
_placeHolderLabel.text = self.placeholder;
[_placeHolderLabel sizeToFit];
[self sendSubviewToBack:_placeHolderLabel];
}
if( [[self text] length] == 0 && [[self placeholder] length] > 0 )
{
[[self viewWithTag:999] setAlpha:1];
}
[super drawRect:rect];
}
@end
其他提示
简单的方法,只是在UITextView
通过使用以下方法UITextViewDelegate
创建的占位符文本:
- (void)textViewDidBeginEditing:(UITextView *)textView
{
if ([textView.text isEqualToString:@"placeholder text here..."]) {
textView.text = @"";
textView.textColor = [UIColor blackColor]; //optional
}
[textView becomeFirstResponder];
}
- (void)textViewDidEndEditing:(UITextView *)textView
{
if ([textView.text isEqualToString:@""]) {
textView.text = @"placeholder text here...";
textView.textColor = [UIColor lightGrayColor]; //optional
}
[textView resignFirstResponder];
}
只是记得设置myUITextView
与创作e.g确切文本。
UITextView *myUITextView = [[UITextView alloc] init];
myUITextView.delegate = self;
myUITextView.text = @"placeholder text here...";
myUITextView.textColor = [UIColor lightGrayColor]; //optional
和使父类UITextViewDelegate
包括这些方法e.g之前。
@interface MyClass () <UITextViewDelegate>
@end
<强>代码夫特3.1 强>
func textViewDidBeginEditing(_ textView: UITextView)
{
if (textView.text == "placeholder text here..." && textView.textColor == .lightGray)
{
textView.text = ""
textView.textColor = .black
}
textView.becomeFirstResponder() //Optional
}
func textViewDidEndEditing(_ textView: UITextView)
{
if (textView.text == "")
{
textView.text = "placeholder text here..."
textView.textColor = .lightGray
}
textView.resignFirstResponder()
}
只是记得设置myUITextView
与创作e.g确切文本。
let myUITextView = UITextView.init()
myUITextView.delegate = self
myUITextView.text = "placeholder text here..."
myUITextView.textColor = .lightGray
和使父类UITextViewDelegate
包括这些方法e.g之前。
class MyClass: UITextViewDelegate
{
}
我是不是太高兴与任何张贴,因为他们是一个有点沉重的解决方案。添加视图的观点不甚理想(特别是在drawRect:
)。他们都有泄漏,这是不能接受的任一。
下面是我的解决方案: SAMTextView
SAMTextView.h
//
// SAMTextView.h
// SAMTextView
//
// Created by Sam Soffes on 8/18/10.
// Copyright 2010-2013 Sam Soffes. All rights reserved.
//
#import <UIKit/UIKit.h>
/**
UITextView subclass that adds placeholder support like UITextField has.
*/
@interface SAMTextView : UITextView
/**
The string that is displayed when there is no other text in the text view.
The default value is `nil`.
*/
@property (nonatomic, strong) NSString *placeholder;
/**
The color of the placeholder.
The default is `[UIColor lightGrayColor]`.
*/
@property (nonatomic, strong) UIColor *placeholderTextColor;
/**
Returns the drawing rectangle for the text views’s placeholder text.
@param bounds The bounding rectangle of the receiver.
@return The computed drawing rectangle for the placeholder text.
*/
- (CGRect)placeholderRectForBounds:(CGRect)bounds;
@end
SAMTextView.m
//
// SAMTextView.m
// SAMTextView
//
// Created by Sam Soffes on 8/18/10.
// Copyright 2010-2013 Sam Soffes. All rights reserved.
//
#import "SAMTextView.h"
@implementation SAMTextView
#pragma mark - Accessors
@synthesize placeholder = _placeholder;
@synthesize placeholderTextColor = _placeholderTextColor;
- (void)setText:(NSString *)string {
[super setText:string];
[self setNeedsDisplay];
}
- (void)insertText:(NSString *)string {
[super insertText:string];
[self setNeedsDisplay];
}
- (void)setAttributedText:(NSAttributedString *)attributedText {
[super setAttributedText:attributedText];
[self setNeedsDisplay];
}
- (void)setPlaceholder:(NSString *)string {
if ([string isEqual:_placeholder]) {
return;
}
_placeholder = string;
[self setNeedsDisplay];
}
- (void)setContentInset:(UIEdgeInsets)contentInset {
[super setContentInset:contentInset];
[self setNeedsDisplay];
}
- (void)setFont:(UIFont *)font {
[super setFont:font];
[self setNeedsDisplay];
}
- (void)setTextAlignment:(NSTextAlignment)textAlignment {
[super setTextAlignment:textAlignment];
[self setNeedsDisplay];
}
#pragma mark - NSObject
- (void)dealloc {
[[NSNotificationCenter defaultCenter] removeObserver:self name:UITextViewTextDidChangeNotification object:self];
}
#pragma mark - UIView
- (id)initWithCoder:(NSCoder *)aDecoder {
if ((self = [super initWithCoder:aDecoder])) {
[self initialize];
}
return self;
}
- (id)initWithFrame:(CGRect)frame {
if ((self = [super initWithFrame:frame])) {
[self initialize];
}
return self;
}
- (void)drawRect:(CGRect)rect {
[super drawRect:rect];
if (self.text.length == 0 && self.placeholder) {
rect = [self placeholderRectForBounds:self.bounds];
UIFont *font = self.font ? self.font : self.typingAttributes[NSFontAttributeName];
// Draw the text
[self.placeholderTextColor set];
[self.placeholder drawInRect:rect withFont:font lineBreakMode:NSLineBreakByTruncatingTail alignment:self.textAlignment];
}
}
#pragma mark - Placeholder
- (CGRect)placeholderRectForBounds:(CGRect)bounds {
// Inset the rect
CGRect rect = UIEdgeInsetsInsetRect(bounds, self.contentInset);
if (self.typingAttributes) {
NSParagraphStyle *style = self.typingAttributes[NSParagraphStyleAttributeName];
if (style) {
rect.origin.x += style.headIndent;
rect.origin.y += style.firstLineHeadIndent;
}
}
return rect;
}
#pragma mark - Private
- (void)initialize {
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(textChanged:) name:UITextViewTextDidChangeNotification object:self];
self.placeholderTextColor = [UIColor colorWithWhite:0.702f alpha:1.0f];
}
- (void)textChanged:(NSNotification *)notification {
[self setNeedsDisplay];
}
@end
这是比别人更简单了很多,因为它不使用子视图(或有泄漏)。随意使用它。
<强>更新11/10/11:强>它现在记录,并支持在界面生成器使用
<强>更新13年11月24日:强>点至新回购
你可以做的是建立与在text
属性一些初始值的文本视图,并更改textColor
到[UIColor grayColor]
或类似的东西。然后,每当文本视图变为可编辑,清除文本,并呈现出光标,如果文本字段是有史以来空一遍,把你的占位符文本回来。改变颜色为[UIColor blackColor]
适当。
它不完全等同于一个的UITextField占位符的功能,但是它很接近。
我发现自己有一种非常简单的方法来模仿占位符
- 在NIB或代码中将textView的textColor设置为lightGrayColor(大多数时候)
- 确保您的 textView 的委托链接到文件的所有者并在头文件中实现 UITextViewDelegate
- 将文本视图的默认文本设置为(例如:“Foobar 占位符”)
- 实施:(BOOL) textViewShouldBeginEditing:(UITextView *)textView
编辑:
更改了 if 语句以比较标签而不是文本。如果用户删除了文本,也可能会意外删除占位符的一部分 @"Foobar placeholder"
这意味着如果用户重新输入 textView 以下委托方法, -(BOOL) textViewShouldBeginEditing:(UITextView *) textView
, ,它不会按预期工作。我尝试通过 if 语句中的文本颜色进行比较,但发现界面生成器中设置的浅灰色与代码中设置的浅灰色不同 [UIColor lightGreyColor]
- (BOOL) textViewShouldBeginEditing:(UITextView *)textView
{
if(textView.tag == 0) {
textView.text = @"";
textView.textColor = [UIColor blackColor];
textView.tag = 1;
}
return YES;
}
当键盘返回且 [textView length] == 0 时,也可以重置占位符文本
编辑:
只是为了让最后一部分更清晰 - 以下是如何设置占位符文本:
- (void)textViewDidChange:(UITextView *)textView
{
if([textView.text length] == 0)
{
textView.text = @"Foobar placeholder";
textView.textColor = [UIColor lightGrayColor];
textView.tag = 0;
}
}
可以通过
上设置UITextView
标签
[UITextView addSubView:lblPlaceHoldaer];
和隐藏它TextViewdidChange
方法。
这是简单和容易的方法。
如果有人需要用于夫特一个解决方案:
添加到UITextViewDelegate类
var placeHolderText = "Placeholder Text..."
override func viewDidLoad() {
super.viewDidLoad()
textView.delegate = self
}
func textViewShouldBeginEditing(textView: UITextView) -> Bool {
self.textView.textColor = .black
if(self.textView.text == placeHolderText) {
self.textView.text = ""
}
return true
}
func textViewDidEndEditing(textView: UITextView) {
if(textView.text == "") {
self.textView.text = placeHolderText
self.textView.textColor = .lightGray
}
}
override func viewWillAppear(animated: Bool) {
if(currentQuestion.answerDisplayValue == "") {
self.textView.text = placeHolderText
self.textView.textColor = .lightGray
} else {
self.textView.text = "xxx" // load default text / or stored
self.textView.textColor = .black
}
}
简单的夫特3 强>溶液
添加到UITextViewDelegate
类
设置yourTextView.delegate = self
创建placeholderLabel
和它里面yourTextView
位置
现在只是动画上placeholderLabel.alpha
textViewDidChange
:
func textViewDidChange(_ textView: UITextView) {
let newAlpha: CGFloat = textView.text.isEmpty ? 1 : 0
if placeholderLabel.alpha != newAlpha {
UIView.animate(withDuration: 0.3) {
self.placeholderLabel.alpha = newAlpha
}
}
}
你可能有placeholderLabel
地位,发挥来设置它的权利,但不应该太硬
我伸出KmKndy的答案,所以直到用户开始编辑UITextView
而不仅仅是水龙头就可以了占位符仍然可见。这反映了在Twitter和Facebook应用程序的功能。我的解决方案不要求你的子类和工作,如果用户键入直接或粘贴文本!
- (void)textViewDidChangeSelection:(UITextView *)textView{
if ([textView.text isEqualToString:@"What's happening?"] && [textView.textColor isEqual:[UIColor lightGrayColor]])[textView setSelectedRange:NSMakeRange(0, 0)];
}
- (void)textViewDidBeginEditing:(UITextView *)textView{
[textView setSelectedRange:NSMakeRange(0, 0)];
}
- (void)textViewDidChange:(UITextView *)textView
{
if (textView.text.length != 0 && [[textView.text substringFromIndex:1] isEqualToString:@"What's happening?"] && [textView.textColor isEqual:[UIColor lightGrayColor]]){
textView.text = [textView.text substringToIndex:1];
textView.textColor = [UIColor blackColor]; //optional
}
else if(textView.text.length == 0){
textView.text = @"What's happening?";
textView.textColor = [UIColor lightGrayColor];
[textView setSelectedRange:NSMakeRange(0, 0)];
}
}
- (void)textViewDidEndEditing:(UITextView *)textView
{
if ([textView.text isEqualToString:@""]) {
textView.text = @"What's happening?";
textView.textColor = [UIColor lightGrayColor]; //optional
}
[textView resignFirstResponder];
}
- (BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)text{
if (textView.text.length > 1 && [textView.text isEqualToString:@"What's happening?"]) {
textView.text = @"";
textView.textColor = [UIColor blackColor];
}
return YES;
}
只是记得设置myUITextView与创作e.g确切文本。
UITextView *myUITextView = [[UITextView alloc] init];
myUITextView.delegate = self;
myUITextView.text = @"What's happening?";
myUITextView.textColor = [UIColor lightGrayColor]; //optional
和使父类一个UITextView委托包括这些方法e.g之前。
@interface MyClass () <UITextViewDelegate>
@end
我建议使用SZTextView
。
https://github.com/glaszig/SZTextView
从UITextView
添加默认storyboard
,然后改变其自定义类SZTextView
像下面
下面是“SAMTextView”ObjC 代码的 Swift 端口,作为该问题的第一批回复之一发布。我在 iOS 8 上测试过。我调整了一些东西,包括占位符文本放置的边界偏移,因为原始文本太高且太右(在该帖子的评论之一中使用了建议)。
我知道有很多简单的解决方案,但我喜欢子类化 UITextView 的方法,因为它是可重用的,而且我不必用机制来混淆使用它的类。
斯威夫特 2.2:
import UIKit
class PlaceholderTextView: UITextView {
@IBInspectable var placeholderColor: UIColor = UIColor.lightGrayColor()
@IBInspectable var placeholderText: String = ""
override var font: UIFont? {
didSet {
setNeedsDisplay()
}
}
override var contentInset: UIEdgeInsets {
didSet {
setNeedsDisplay()
}
}
override var textAlignment: NSTextAlignment {
didSet {
setNeedsDisplay()
}
}
override var text: String? {
didSet {
setNeedsDisplay()
}
}
override var attributedText: NSAttributedString? {
didSet {
setNeedsDisplay()
}
}
required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
setUp()
}
override init(frame: CGRect, textContainer: NSTextContainer?) {
super.init(frame: frame, textContainer: textContainer)
}
private func setUp() {
NSNotificationCenter.defaultCenter().addObserver(self, selector: #selector(PlaceholderTextView.textChanged(_:)),
name: UITextViewTextDidChangeNotification, object: self)
}
func textChanged(notification: NSNotification) {
setNeedsDisplay()
}
func placeholderRectForBounds(bounds: CGRect) -> CGRect {
var x = contentInset.left + 4.0
var y = contentInset.top + 9.0
let w = frame.size.width - contentInset.left - contentInset.right - 16.0
let h = frame.size.height - contentInset.top - contentInset.bottom - 16.0
if let style = self.typingAttributes[NSParagraphStyleAttributeName] as? NSParagraphStyle {
x += style.headIndent
y += style.firstLineHeadIndent
}
return CGRect(x: x, y: y, width: w, height: h)
}
override func drawRect(rect: CGRect) {
if text!.isEmpty && !placeholderText.isEmpty {
let paragraphStyle = NSMutableParagraphStyle()
paragraphStyle.alignment = textAlignment
let attributes: [ String: AnyObject ] = [
NSFontAttributeName : font!,
NSForegroundColorAttributeName : placeholderColor,
NSParagraphStyleAttributeName : paragraphStyle]
placeholderText.drawInRect(placeholderRectForBounds(bounds), withAttributes: attributes)
}
super.drawRect(rect)
}
}
斯威夫特 4.2:
import UIKit
class PlaceholderTextView: UITextView {
@IBInspectable var placeholderColor: UIColor = UIColor.lightGray
@IBInspectable var placeholderText: String = ""
override var font: UIFont? {
didSet {
setNeedsDisplay()
}
}
override var contentInset: UIEdgeInsets {
didSet {
setNeedsDisplay()
}
}
override var textAlignment: NSTextAlignment {
didSet {
setNeedsDisplay()
}
}
override var text: String? {
didSet {
setNeedsDisplay()
}
}
override var attributedText: NSAttributedString? {
didSet {
setNeedsDisplay()
}
}
required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
setUp()
}
override init(frame: CGRect, textContainer: NSTextContainer?) {
super.init(frame: frame, textContainer: textContainer)
}
private func setUp() {
NotificationCenter.default.addObserver(self,
selector: #selector(self.textChanged(notification:)),
name: Notification.Name("UITextViewTextDidChangeNotification"),
object: nil)
}
@objc func textChanged(notification: NSNotification) {
setNeedsDisplay()
}
func placeholderRectForBounds(bounds: CGRect) -> CGRect {
var x = contentInset.left + 4.0
var y = contentInset.top + 9.0
let w = frame.size.width - contentInset.left - contentInset.right - 16.0
let h = frame.size.height - contentInset.top - contentInset.bottom - 16.0
if let style = self.typingAttributes[NSAttributedString.Key.paragraphStyle] as? NSParagraphStyle {
x += style.headIndent
y += style.firstLineHeadIndent
}
return CGRect(x: x, y: y, width: w, height: h)
}
override func draw(_ rect: CGRect) {
if text!.isEmpty && !placeholderText.isEmpty {
let paragraphStyle = NSMutableParagraphStyle()
paragraphStyle.alignment = textAlignment
let attributes: [NSAttributedString.Key: Any] = [
NSAttributedString.Key(rawValue: NSAttributedString.Key.font.rawValue) : font!,
NSAttributedString.Key(rawValue: NSAttributedString.Key.foregroundColor.rawValue) : placeholderColor,
NSAttributedString.Key(rawValue: NSAttributedString.Key.paragraphStyle.rawValue) : paragraphStyle]
placeholderText.draw(in: placeholderRectForBounds(bounds: bounds), withAttributes: attributes)
}
super.draw(rect)
}
}
这是我如何做到了:
UITextView2.h
#import <UIKit/UIKit.h>
@interface UITextView2 : UITextView <UITextViewDelegate> {
NSString *placeholder;
UIColor *placeholderColor;
}
@property(nonatomic, retain) NSString *placeholder;
@property(nonatomic, retain) UIColor *placeholderColor;
-(void)textChanged:(NSNotification*)notif;
@end
UITextView2.m
@implementation UITextView2
@synthesize placeholder, placeholderColor;
- (id)initWithFrame:(CGRect)frame {
if (self = [super initWithFrame:frame]) {
[self setPlaceholder:@""];
[self setPlaceholderColor:[UIColor lightGrayColor]];
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(textChanged:) name:UITextViewTextDidChangeNotification object:nil];
}
return self;
}
-(void)textChanged:(NSNotification*)notif {
if ([[self placeholder] length]==0)
return;
if ([[self text] length]==0) {
[[self viewWithTag:999] setAlpha:1];
} else {
[[self viewWithTag:999] setAlpha:0];
}
}
- (void)drawRect:(CGRect)rect {
if ([[self placeholder] length]>0) {
UILabel *l = [[UILabel alloc] initWithFrame:CGRectMake(8, 8, 0, 0)];
[l setFont:self.font];
[l setTextColor:self.placeholderColor];
[l setText:self.placeholder];
[l setAlpha:0];
[l setTag:999];
[self addSubview:l];
[l sizeToFit];
[self sendSubviewToBack:l];
[l release];
}
if ([[self text] length]==0 && [[self placeholder] length]>0) {
[[self viewWithTag:999] setAlpha:1];
}
[super drawRect:rect];
}
- (void)dealloc {
[[NSNotificationCenter defaultCenter] removeObserver:self];
[super dealloc];
}
@end
下面是一个比较容易的方式解决,其行为完全一样的UITextField的占位符,但并不需要绘制自定义视图,或辞职第一响应者。
- (void) textViewDidChange:(UITextView *)textView{
if (textView.text.length == 0){
textView.textColor = [UIColor lightGrayColor];
textView.text = placeholderText;
[textView setSelectedRange:NSMakeRange(0, 0)];
isPlaceholder = YES;
} else if (isPlaceholder && ![textView.text isEqualToString:placeholderText]) {
textView.text = [textView.text substringToIndex:1];
textView.textColor = [UIColor blackColor];
isPlaceholder = NO;
}
}
(在else第二检查if语句是用于在其中输入无关的情况下和用户按下退格键)
只要设置你的类作为UITextViewDelegate。在viewDidLoad中你应该初始化像
- (void) viewDidLoad{
// initialize placeholder text
placeholderText = @"some placeholder";
isPlaceholder = YES;
self.someTextView.text = placeholderText;
self.someTextView.textColor = [UIColor lightGrayColor];
[self.someTextView setSelectedRange:NSMakeRange(0, 0)];
// assign UITextViewDelegate
self.someTextView.delegate = self;
}
抱歉添加另一个答案,但我只是拉这样的事情关闭,这创造最接近到的UITextField一种占位符。
希望这可以帮助别人。
-(void)textViewDidChange:(UITextView *)textView{
if(textView.textColor == [UIColor lightGrayColor]){
textView.textColor = [UIColor blackColor]; // look at the comment section in this answer
textView.text = [textView.text substringToIndex: 0];// look at the comment section in this answer
}else if(textView.text.length == 0){
textView.text = @"This is some placeholder text.";
textView.textColor = [UIColor lightGrayColor];
textView.selectedRange = NSMakeRange(0, 0);
}
}
-(void)textViewDidChangeSelection:(UITextView *)textView{
if(textView.textColor == [UIColor lightGrayColor] && (textView.selectedRange.location != 0 || textView.selectedRange.length != 0)){
textView.selectedRange = NSMakeRange(0, 0);
}
}
嗨,你可以使用IQKeyboard Manager中提供IQTextView它使用简单,只需设置你的类中的TextView集成到IQTextView,你可以使用它的属性设置占位符标签你想要的颜色。 您可以从 IQKeyboardManager
下载库,也可以从的CocoaPods安装。
简单的方式来一些行代码中使用该
取一个标签到的UITextView在笔尖 这个标签连接到你的代码, 后它。
- (BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)text{
if (range.location>0 || text.length!=0) {
placeholderLabel1.hidden = YES;
}else{
placeholderLabel1.hidden = NO;
}
return YES;
}
我修改萨姆Soffes'实现与iOS7工作:
- (void)drawRect:(CGRect)rect
{
[super drawRect:rect];
if (_shouldDrawPlaceholder)
{
UIEdgeInsets insets = self.textContainerInset;
CGRect placeholderRect = CGRectMake(
insets.left + self.textContainer.lineFragmentPadding,
insets.top,
self.frame.size.width - insets.left - insets.right,
self.frame.size.height - insets.top - insets.bottom);
[_placeholderText drawWithRect:placeholderRect
options:NSStringDrawingUsesLineFragmentOrigin | NSStringDrawingTruncatesLastVisibleLine
attributes:self.placeholderAttributes
context:nil];
}
}
- (NSDictionary *)placeholderAttributes
{
if (_placeholderAttributes == nil)
{
_placeholderAttributes = @
{
NSFontAttributeName : self.font,
NSForegroundColorAttributeName : self.placeholderColor
};
}
return _placeholderAttributes;
}
记得设置_placeholderAttribues = nil
在可能改变字体和可能影响它们的其他thigns方法。您可能还需要跳过属性的“懒”制作字典如果没有打扰你。
修改强>
记住,如果你喜欢的占位符自动版式动画等照顾好叫setNeedsDisplay中的setBounds的重写版本。
您也可以创建一个新的类TextViewWithPlaceholder作为UITextView中的一个子类。
(此代码是一种粗糙的 - 但我认为这是正确的轨道上)
@interface TextViewWithPlaceholder : UITextView
{
NSString *placeholderText; // make a property
UIColor *placeholderColor; // make a property
UIColor *normalTextColor; // cache text color here whenever you switch to the placeholderColor
}
- (void) setTextColor: (UIColor*) color
{
normalTextColor = color;
[super setTextColor: color];
}
- (void) updateForTextChange
{
if ([self.text length] == 0)
{
normalTextColor = self.textColor;
self.textColor = placeholderColor;
self.text = placeholderText;
}
else
{
self.textColor = normalTextColor;
}
}
在您的委托,补充一点:
- (void)textViewDidChange:(UITextView *)textView
{
if ([textView respondsToSelector: @selector(updateForTextChange)])
{
[textView updateForTextChange];
}
}
我做我自己“的UITextView”的子类的版本。我喜欢使用的通知山姆Soffes 的想法,但我并不喜欢的drawRect:覆盖。矫枉过正在我看来。我觉得我做了一个非常干净的实现。
您可以看看我的子类这里。演示项目也包括在内。
该线程已经有很多答案,但这里是我比较喜欢的版本。
据延长现有UITextView
类,所以很容易重复使用,并且它的不的拦截像textViewDidChange
的事件(这可能会破坏用户的代码,如果他们已经截获别处这些事件)。
使用我的代码(如下图所示),你可以轻松地添加一个占位符,以任何你UITextViews
的是这样的:
self.textViewComments.placeholder = @"(Enter some comments here.)";
当您设置这个新的占位符值,它悄悄地增加你的UILabel
顶部的UITextView
,然后隐藏/显示它作为必要的:
好,进行这些改变,添加含有该代码“UITextViewHelper.h”文件:
// UITextViewHelper.h
// Created by Michael Gledhill on 13/02/15.
#import <Foundation/Foundation.h>
@interface UITextView (UITextViewHelper)
@property (nonatomic, strong) NSString* placeholder;
@property (nonatomic, strong) UILabel* placeholderLabel;
@property (nonatomic, strong) NSString* textValue;
-(void)checkIfNeedToDisplayPlaceholder;
@end
...和含有此一UITextViewHelper.m文件:
// UITextViewHelper.m
// Created by Michael Gledhill on 13/02/15.
//
// This UITextView category allows us to easily display a PlaceHolder string in our UITextView.
// The downside is that, your code needs to set the "textValue" rather than the "text" value to safely set the UITextView's text.
//
#import "UITextViewHelper.h"
#import <objc/runtime.h>
@implementation UITextView (UITextViewHelper)
#define UI_PLACEHOLDER_TEXT_COLOR [UIColor colorWithRed:170.0/255.0 green:170.0/255.0 blue:170.0/255.0 alpha:1.0]
@dynamic placeholder;
@dynamic placeholderLabel;
@dynamic textValue;
-(void)setTextValue:(NSString *)textValue
{
// Change the text of our UITextView, and check whether we need to display the placeholder.
self.text = textValue;
[self checkIfNeedToDisplayPlaceholder];
}
-(NSString*)textValue
{
return self.text;
}
-(void)checkIfNeedToDisplayPlaceholder
{
// If our UITextView is empty, display our Placeholder label (if we have one)
if (self.placeholderLabel == nil)
return;
self.placeholderLabel.hidden = (![self.text isEqualToString:@""]);
}
-(void)onTap
{
// When the user taps in our UITextView, we'll see if we need to remove the placeholder text.
[self checkIfNeedToDisplayPlaceholder];
// Make the onscreen keyboard appear.
[self becomeFirstResponder];
}
-(void)keyPressed:(NSNotification*)notification
{
// The user has just typed a character in our UITextView (or pressed the delete key).
// Do we need to display our Placeholder label ?
[self checkIfNeedToDisplayPlaceholder];
}
#pragma mark - Add a "placeHolder" string to the UITextView class
NSString const *kKeyPlaceHolder = @"kKeyPlaceHolder";
-(void)setPlaceholder:(NSString *)_placeholder
{
// Sets our "placeholder" text string, creates a new UILabel to contain it, and modifies our UITextView to cope with
// showing/hiding the UILabel when needed.
objc_setAssociatedObject(self, &kKeyPlaceHolder, (id)_placeholder, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
self.placeholderLabel = [[UILabel alloc] initWithFrame:self.frame];
self.placeholderLabel.numberOfLines = 1;
self.placeholderLabel.text = _placeholder;
self.placeholderLabel.textColor = UI_PLACEHOLDER_TEXT_COLOR;
self.placeholderLabel.backgroundColor = [UIColor clearColor];
self.placeholderLabel.userInteractionEnabled = true;
self.placeholderLabel.font = self.font;
[self addSubview:self.placeholderLabel];
[self.placeholderLabel sizeToFit];
// Whenever the user taps within the UITextView, we'll give the textview the focus, and hide the placeholder if necessary.
[self addGestureRecognizer:[[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(onTap)]];
// Whenever the user types something in the UITextView, we'll see if we need to hide/show the placeholder label.
[[NSNotificationCenter defaultCenter] addObserver:self selector: @selector(keyPressed:) name:UITextViewTextDidChangeNotification object:nil];
[self checkIfNeedToDisplayPlaceholder];
}
-(NSString*)placeholder
{
// Returns our "placeholder" text string
return objc_getAssociatedObject(self, &kKeyPlaceHolder);
}
#pragma mark - Add a "UILabel" to this UITextView class
NSString const *kKeyLabel = @"kKeyLabel";
-(void)setPlaceholderLabel:(UILabel *)placeholderLabel
{
// Stores our new UILabel (which contains our placeholder string)
objc_setAssociatedObject(self, &kKeyLabel, (id)placeholderLabel, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
[[NSNotificationCenter defaultCenter] addObserver:self selector: @selector(keyPressed:) name:UITextViewTextDidChangeNotification object:nil];
[self checkIfNeedToDisplayPlaceholder];
}
-(UILabel*)placeholderLabel
{
// Returns our new UILabel
return objc_getAssociatedObject(self, &kKeyLabel);
}
@end
是啊,这是一个很大的代码,但一旦它添加到您的项目,包括.h文件...
#import "UITextViewHelper.h"
...你可以很容易地在UITextViews
使用占位符。
还有一个疑难杂症虽然。
如果你这样做:
self.textViewComments.placeholder = @"(Enter some comments here.)";
self.textViewComments.text = @"Ooooh, hello there";
...占位符会出现的在的文本的顶部。当您设置text
值,没有定期的通知会被调用,所以我不能工作,如何调用我的功能来决定是否显示/隐藏占位符。
的解决方案是设置textValue
而非text
:
self.textViewComments.placeholder = @"(Enter some comments here.)";
self.textViewComments.textValue = @"Ooooh, hello there";
可替换地,可以设置text
值,则调用checkIfNeedToDisplayPlaceholder
。
self.textViewComments.text = @"Ooooh, hello there";
[self.textViewComments checkIfNeedToDisplayPlaceholder];
我喜欢这样的解决方案,因为他们“行云流水”之间苹果公司为我们提供了,和我们(如开发商)的实际需要的在我们的应用程序。你写这样的代码一次,将其添加到您的“帮手”的.m / .h文件库,并且,随着时间的推移,该SDK居然开始变得不那么令人沮丧。
(我写过类似的帮手加入了“清除”按钮,我UITextViews,这烦人存在于UITextField
但另一件事不是在UITextView
...)
首先采取在h文件的标签。
下面我采取
UILabel * lbl;
然后,在viewDidLoad中下的.m声明它
lbl = [[UILabel alloc] initWithFrame:CGRectMake(8.0, 0.0,250, 34.0)];
lbl.font=[UIFont systemFontOfSize:14.0];
[lbl setText:@"Write a message..."];
[lbl setBackgroundColor:[UIColor clearColor]];
[lbl setTextColor:[UIColor lightGrayColor]];
[textview addSubview:lbl];
TextView的是我的TextView。
现在声明
-(void)textViewDidChange:(UITextView *)textView {
if (![textView hasText]){
lbl.hidden = NO;
}
else{
lbl.hidden = YES;
}
}
和你的TextView占位符是准备好了!
我建议使用荚 '的UITextView +占位符'
pod 'UITextView+Placeholder'
您的代码
#import "UITextView+Placeholder.h"
////
UITextView *textView = [[UITextView alloc] init];
textView.placeholder = @"How are you?";
textView.placeholderColor = [UIColor lightGrayColor];
- (void)textViewDidChange:(UITextView *)textView
{
placeholderLabel.hidden = YES;
}
放置一个标签在TextView的。
这是不可能在UITextView的创建的占位符,但可以通过此产生等占位效应。
- (void)viewDidLoad{
commentTxtView.text = @"Comment";
commentTxtView.textColor = [UIColor lightGrayColor];
commentTxtView.delegate = self;
}
- (BOOL) textViewShouldBeginEditing:(UITextView *)textView
{
commentTxtView.text = @"";
commentTxtView.textColor = [UIColor blackColor];
return YES;
}
-(void) textViewDidChange:(UITextView *)textView
{
if(commentTxtView.text.length == 0){
commentTxtView.textColor = [UIColor lightGrayColor];
commentTxtView.text = @"Comment";
[commentTxtView resignFirstResponder];
}
}
或你可以在TextView中添加标签,就像
lbl = [[UILabel alloc] initWithFrame:CGRectMake(10.0, 0.0,textView.frame.size.width - 10.0, 34.0)];
[lbl setText:kDescriptionPlaceholder];
[lbl setBackgroundColor:[UIColor clearColor]];
[lbl setTextColor:[UIColor lightGrayColor]];
textView.delegate = self;
[textView addSubview:lbl];
并设置强>
- (void)textViewDidEndEditing:(UITextView *)theTextView
{
if (![textView hasText]) {
lbl.hidden = NO;
}
}
- (void) textViewDidChange:(UITextView *)textView
{
if(![textView hasText]) {
lbl.hidden = NO;
}
else{
lbl.hidden = YES;
}
}
这模仿的UITextField的占位符完美,这里的占位符文本保持,直到你真正输入一些东西。
private let placeholder = "Type here"
@IBOutlet weak var textView: UITextView! {
didSet {
textView.textColor = UIColor.lightGray
textView.text = placeholder
textView.selectedRange = NSRange(location: 0, length: 0)
}
}
extension ViewController: UITextViewDelegate {
func textViewDidChangeSelection(_ textView: UITextView) {
// Move cursor to beginning on first tap
if textView.text == placeholder {
textView.selectedRange = NSRange(location: 0, length: 0)
}
}
func textView(_ textView: UITextView, shouldChangeTextIn range: NSRange, replacementText text: String) -> Bool {
if textView.text == placeholder && !text.isEmpty {
textView.text = nil
textView.textColor = UIColor.black
textView.selectedRange = NSRange(location: 0, length: 0)
}
return true
}
func textViewDidChange(_ textView: UITextView) {
if textView.text.isEmpty {
textView.textColor = UIColor.lightGray
textView.text = placeholder
}
}
}
下面是另一种方式做到这一点,一个再现UITextField
的占位符的轻微压痕:
,使得它们的左上拐角对准拖动UITextField
权利UITextView
下。您的占位符文本添加到文本字段。
在viewDidLoad中,添加:
[tView setDelegate:self];
tView.contentInset = UIEdgeInsetsMake(-8,-8,0,0);
tView.backgroundColor = [UIColor clearColor];
然后加入:
- (void)textViewDidChange:(UITextView *)textView {
if (textView.text.length == 0) {
textView.backgroundColor = [UIColor clearColor];
} else {
textView.backgroundColor = [UIColor whiteColor];
}
}
允许可以很容易
创建一个的UILabel,并把它放在你的文本视图(给文字的占位符集灰色,你可以做到这一切在你的XIB) 现在,在你头文件声明的UILabel,也是在textviewDelegate 现在,你可以简单地隐藏标签,当你点击的TextView
下面完整代码
头
@interface ViewController :UIViewController<UITextViewDelegate>{
}
@property (nonatomic,strong) IBOutlet UILabel *PlceHolder_label;
@property (nonatomic,strong) IBOutlet UITextView *TextView;
@end
实施
@implementation UploadFoodImageViewController
@synthesize PlceHolder_label,TextView;
- (void)viewDidLoad
{
[super viewDidLoad];
}
- (BOOL)textViewShouldBeginEditing:(UITextView *)textView{
if([textView isEqual:TextView]){
[PlceHolder_label setHidden:YES];
[self.tabScrlVw setContentOffset:CGPointMake(0,150) animated:YES];
}
return YES;
}
@end
不要忘记连接TextView的和的UILabel从XIB到filesowner
看一眼 UTP占位符文本视图.
这是 UITextView 的一个方便的子类,它支持与 UITextField 类似的占位符。主要特点:
- 不使用子视图
- 不重写drawRect:
- 占位符可以是任意长度,并以与通常文本相同的方式呈现
我经历了所有这些阅读,但在很短的,斯威夫特3,解决方案,在所有我的测试工作已经来到了。它可以站在多一点共性,但这个过程很简单。下面是我称之为“TextViewWithPlaceholder”。
整个事情import UIKit
class TextViewWithPlaceholder: UITextView {
public var placeholder: String?
public var placeholderColor = UIColor.lightGray
private var placeholderLabel: UILabel?
// Set up notification listener when created from a XIB or storyboard.
// You can also set up init() functions if you plan on creating
// these programmatically.
override func awakeFromNib() {
super.awakeFromNib()
NotificationCenter.default.addObserver(self,
selector: #selector(TextViewWithPlaceholder.textDidChangeHandler(notification:)),
name: .UITextViewTextDidChange,
object: self)
placeholderLabel = UILabel()
placeholderLabel?.alpha = 0.85
placeholderLabel?.textColor = placeholderColor
}
// By using layoutSubviews, you can size and position the placeholder
// more accurately. I chose to hard-code the size of the placeholder
// but you can combine this with other techniques shown in previous replies.
override func layoutSubviews() {
super.layoutSubviews()
placeholderLabel?.textColor = placeholderColor
placeholderLabel?.text = placeholder
placeholderLabel?.frame = CGRect(x: 6, y: 4, width: self.bounds.size.width-16, height: 24)
if text.isEmpty {
addSubview(placeholderLabel!)
bringSubview(toFront: placeholderLabel!)
} else {
placeholderLabel?.removeFromSuperview()
}
}
// Whenever the text changes, just trigger a new layout pass.
func textDidChangeHandler(notification: Notification) {
layoutSubviews()
}
}
我在迅速写了一个类。在需要时您可以导入这个类。
import UIKit
公共类CustomTextView:UITextView的{
private struct Constants {
static let defaultiOSPlaceholderColor = UIColor(red: 0.0, green: 0.0, blue: 0.0980392, alpha: 0.22)
}
private let placeholderLabel: UILabel = UILabel()
private var placeholderLabelConstraints = [NSLayoutConstraint]()
@IBInspectable public var placeholder: String = "" {
didSet {
placeholderLabel.text = placeholder
}
}
@IBInspectable public var placeholderColor: UIColor = CustomTextView.Constants.defaultiOSPlaceholderColor {
didSet {
placeholderLabel.textColor = placeholderColor
}
}
override public var font: UIFont! {
didSet {
placeholderLabel.font = font
}
}
override public var textAlignment: NSTextAlignment {
didSet {
placeholderLabel.textAlignment = textAlignment
}
}
override public var text: String! {
didSet {
textDidChange()
}
}
override public var attributedText: NSAttributedString! {
didSet {
textDidChange()
}
}
override public var textContainerInset: UIEdgeInsets {
didSet {
updateConstraintsForPlaceholderLabel()
}
}
override public init(frame: CGRect, textContainer: NSTextContainer?) {
super.init(frame: frame, textContainer: textContainer)
commonInit()
}
required public init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
commonInit()
}
private func commonInit() {
NSNotificationCenter.defaultCenter().addObserver(self,
selector: #selector(textDidChange),
name: UITextViewTextDidChangeNotification,
object: nil)
placeholderLabel.font = font
placeholderLabel.textColor = placeholderColor
placeholderLabel.textAlignment = textAlignment
placeholderLabel.text = placeholder
placeholderLabel.numberOfLines = 0
placeholderLabel.backgroundColor = UIColor.clearColor()
placeholderLabel.translatesAutoresizingMaskIntoConstraints = false
addSubview(placeholderLabel)
updateConstraintsForPlaceholderLabel()
}
private func updateConstraintsForPlaceholderLabel() {
var newConstraints = NSLayoutConstraint.constraintsWithVisualFormat("H:|-(\(textContainerInset.left + textContainer.lineFragmentPadding))-[placeholder]",
options: [],
metrics: nil,
views: ["placeholder": placeholderLabel])
newConstraints += NSLayoutConstraint.constraintsWithVisualFormat("V:|-(\(textContainerInset.top))-[placeholder]",
options: [],
metrics: nil,
views: ["placeholder": placeholderLabel])
newConstraints.append(NSLayoutConstraint(
item: placeholderLabel,
attribute: .Width,
relatedBy: .Equal,
toItem: self,
attribute: .Width,
multiplier: 1.0,
constant: -(textContainerInset.left + textContainerInset.right + textContainer.lineFragmentPadding * 2.0)
))
removeConstraints(placeholderLabelConstraints)
addConstraints(newConstraints)
placeholderLabelConstraints = newConstraints
}
@objc private func textDidChange() {
placeholderLabel.hidden = !text.isEmpty
}
public override func layoutSubviews() {
super.layoutSubviews()
placeholderLabel.preferredMaxLayoutWidth = textContainer.size.width - textContainer.lineFragmentPadding * 2.0
}
deinit {
NSNotificationCenter.defaultCenter().removeObserver(self,
name: UITextViewTextDidChangeNotification,
object: nil)
}
}