观察捏多点触摸手势在一个UITableView

Question

我期待实现合拢/缩小一个UITableView的顶部，我也考虑过多种方法，包括这一个：

类似的问题

不过，虽然我可以创建一个UIViewTouch对象，它覆盖到我的UITableView，滚动事件不被转发到我的UITableView，我仍然可以选择单元格，并且它们通过适当的触发一个新的ViewController对象的转变作出反应。但我不能，尽管传递的touchesBegan，touchesMoved滚动的UITableView，并touchesEnded事件。

Answer 1

这似乎是一个经典的问题。在我的情况下，我想在拦截一个UIWebView某些事件不能被继承，等等等等。

我发现，做的最好的办法是使用一个UIWindow拦截的事件：

EventInterceptWindow.h

@protocol EventInterceptWindowDelegate
- (BOOL)interceptEvent:(UIEvent *)event; // return YES if event handled
@end


@interface EventInterceptWindow : UIWindow {
    // It would appear that using the variable name 'delegate' in any UI Kit
    // subclass is a really bad idea because it can occlude the same name in a
    // superclass and silently break things like autorotation.
    id <EventInterceptWindowDelegate> eventInterceptDelegate;
}

@property(nonatomic, assign)
    id <EventInterceptWindowDelegate> eventInterceptDelegate;

@end

EventInterceptWindow.m：

#import "EventInterceptWindow.h"

@implementation EventInterceptWindow

@synthesize eventInterceptDelegate;

- (void)sendEvent:(UIEvent *)event {
    if ([eventInterceptDelegate interceptEvent:event] == NO)
        [super sendEvent:event];
}

@end

创建类，改变类的一个UIWindow在你的MainWindow.xib到EventInterceptWindow，然后某处设置eventInterceptDelegate到要拦截事件视图控制器。实施例截取的双抽头：

- (BOOL)interceptEvent:(UIEvent *)event {
    NSSet *touches = [event allTouches];
    UITouch *oneTouch = [touches anyObject];
    UIView *touchView = [oneTouch view];
    //  NSLog(@"tap count = %d", [oneTouch tapCount]);
    // check for taps on the web view which really end up being dispatched to
    // a scroll view
    if (touchView && [touchView isDescendantOfView:webView]
            && touches && oneTouch.phase == UITouchPhaseBegan) {
        if ([oneTouch tapCount] == 2) {
            [self toggleScreenDecorations];
            return YES;
        }
    }   
    return NO;
}

相关资讯： http://iphoneincubator.com/blog/windows-views/360idev -iPhone开发人员的会议呈递

Answer 2

尼姆罗德写道：

  

某处eventInterceptDelegate设置为要拦截事件视图控制器

我没有立即明白这种说法。对于谁比谁有同样的问题，因为我的利益，我做的方式是通过添加如下代码到我UIView子类必须检测触摸。

- (void) viewDidAppear:(BOOL)animated
{
    [super viewDidAppear:animated];

    // Register to receive touch events
    MyApplicationAppDelegate *appDelegate = (MyApplicationAppDelegate *) [[UIApplication sharedApplication] delegate];
    EventInterceptWindow *window = (EventInterceptWindow *) appDelegate.window;
    window.eventInterceptDelegate = self;
}


- (void) viewWillDisappear:(BOOL) animated
{
    // Deregister from receiving touch events
    MyApplicationAppDelegate *appDelegate = (MyApplicationAppDelegate *) [[UIApplication sharedApplication] delegate];
    EventInterceptWindow *window = (EventInterceptWindow *) appDelegate.window;
    window.eventInterceptDelegate = nil;

    [super viewWillDisappear:animated];
}


- (BOOL) interceptEvent:(UIEvent *) event
{
    NSLog(@"interceptEvent is being called...");
    return NO;
}

，点击 这interceptEvent:的版本是一个简单的实现双指缩放检测。 NB。某些代码被采取从由Apress出版从iPhone 3成长。

CGFloat initialDistance;

- (BOOL) interceptEvent:(UIEvent *) event
{
    NSSet *touches = [event allTouches];

    // Give up if user wasn't using two fingers
    if([touches count] != 2) return NO;

    UITouchPhase phase = ((UITouch *) [touches anyObject]).phase;
    CGPoint firstPoint = [[[touches allObjects] objectAtIndex:0] locationInView:self.view];
    CGPoint secondPoint = [[[touches allObjects] objectAtIndex:1] locationInView:self.view];

    CGFloat deltaX = secondPoint.x - firstPoint.x;
    CGFloat deltaY = secondPoint.y - firstPoint.y;
    CGFloat distance = sqrt(deltaX*deltaX + deltaY*deltaY);

    if(phase == UITouchPhaseBegan)
    {
        initialDistance = distance;
    }
    else if(phase == UITouchPhaseMoved)
    {
        CGFloat currentDistance = distance;
        if(initialDistance == 0) initialDistance = currentDistance;
        else if(currentDistance - initialDistance > kMinimumPinchDelta) NSLog(@"Zoom in");
        else if(initialDistance - currentDistance > kMinimumPinchDelta) NSLog(@"Zoom out");
    }
    else if(phase == UITouchPhaseEnded)
    {
        initialDistance = 0;
    }

    return YES;
}

，点击 编辑：尽管此代码在iPhone模拟器的工作100％的罚款，当我跑了一个iPhone设备上我遇到的有关表格滚动奇怪的错误。如果这也发生在你身上，然后强制interceptEvent:方法在所有情况下返回NO。这意味着超也将处理触摸事件，所幸这并没有打破我的代码。