How can I create a count down timer for cocos2d?
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22-07-2019 - |
Question
I am developing a 2D iPhone game by using cocos2d. I need a countdown timer. How can I create a count down timer in cocos2d?
Solution
Not enough rep to upvote Tom, but he's absolutely right. Within the context of this question, NSTimer is the WRONG solution. The Cocos2d framework provides a scheduler that integrates with other game features like Pause/Resume (and most likely uses NSTimer under the hood).
Example from the above link:
-(id) init
{
if( ! [super init] )
return nil;
// schedule timer
[self schedule: @selector(tick:)];
[self schedule: @selector(tick2:) interval:0.5];
return self;
}
-(void) tick: (CCTime) dt
{
// bla bla bla
}
-(void) tick2: (CCTime) dt
{
// bla bla bla
}
OTHER TIPS
http://www.cocos2d-iphone.org/wiki/doku.php/prog_guide:best_practices
- Try NOT to use Cocoa’s NSTimer. Instead use cocos2d’s own scheduler.
- If you use cocos2d scheduler, you will have:
- automatic pause/resume.
- when the Layer (Scene, Sprite, CocosNode) enters the stage the timer will be automatically activated, and when it leaves the stage it will be automatically deactivated.
- Your target/selector will be called with a delta time...
In cocos 2d there is default update section for timer.
Try this:
[self schedule:@selector(update:)];
- (void)update:(ccTime)dt {
}
For those that want to use NSTimer instead of the "schedule" method, you can create a class such as the following:
ZIMCountdownTicker.h
#import <Foundation/Foundation.h>
extern NSString * const ZIMCountdownTickerTickAction;
extern NSString * const ZIMCountdownTickerResetAction;
@protocol ZIMCountdownTickerProtocol;
/*!
@class ZIMCountdownTicker
@discussion This class creates a countdown ticker.
@updated 2011-03-05
*/
@interface ZIMCountdownTicker : NSObject {
@private
NSTimer *_timer;
id<ZIMCountdownTickerProtocol> _delegate;
NSTimeInterval _interval;
double _period;
double _value;
}
/*!
@method initWithDelegate:withTimeInterval:forTimePeriod:
@discussion This method instantiate an instance of this class with the specified parameters.
@param delegate A reference to a class that has implemented ZIMCountdownTickerProtocol.
@param interval The time interval in seconds to be used when running the countdown ticker.
@param period The time period in seconds for which countdown ticker will run.
@updated 2011-03-05
*/
- (id) initWithDelegate: (id<ZIMCountdownTickerProtocol>)delegate withTimeInterval: (NSTimeInterval)interval forTimePeriod: (double)period;
/*!
@method start
@discussion This method will start the countdown ticker.
@updated 2011-03-05
*/
- (void) start;
/*!
@method stop
@discussion This method will stop the countdown ticker.
@updated 2011-03-05
*/
- (void) stop;
/*!
@method reset
@discussion This method will reset the countdown ticker.
@updated 2011-03-06
*/
- (void) reset;
/*!
@method value
@discussion This method will return the countdown ticker's current value; however, using this method will cause
the ticker to stop.
@return The countdown ticker's current value.
@updated 2011-03-05
*/
- (double) value;
@end
@protocol ZIMCountdownTickerProtocol <NSObject>
@optional
/*!
@method countdownTicker:didUpdateValue:withAction:
@discussion This method will notify the delegate with the current value.
@param ticker A reference to tiggering ticker.
@param value The current value.
@param action The action that tiggered this method.
@updated 2011-03-05
*/
- (void) countdownTicker: (ZIMCountdownTicker *)ticker didUpdateValue: (double)value withAction: (NSString *)action;
/*!
@method countdownTickerDidFinish:
@discussion This method will notify the delegate that the countdown ticker finished.
@param ticker A reference to tiggering ticker.
@updated 2011-03-05
*/
- (void) countdownTickerDidFinish: (ZIMCountdownTicker *)ticker;
@end
ZIMCountdownTicker.m
// Ziminji Classes
#import "ZIMCountdownTicker.h"
NSString * const ZIMCountdownTickerTickAction = @"ticker.tick";
NSString * const ZIMCountdownTickerResetAction = @"ticker.reset";
/*!
@category ZIMCountdownTicker (Private)
@discussion This category defines the prototypes for this class's private methods.
@updated 2011-03-05
*/
@interface ZIMCountdownTicker (Private)
/*!
@method countdown:
@discussion This method is called by the timer to decrement the counter's value and will send
the delegate the updated value.
@param timer The timer currently in use.
@updated 2011-03-06
*/
- (void) countdown: (NSTimer *)timer;
@end
@implementation ZIMCountdownTicker
- (id) initWithDelegate: (id<ZIMCountdownTickerProtocol>)delegate withTimeInterval (NSTimeInterval)interval forTimePeriod: (double)period {
if (self = [super init]) {
_delegate = delegate;
_interval = interval;
_period = period;
_value = period;
_timer = nil;
}
return self;
}
- (void) start {
if (_timer == nil) {
_timer = [NSTimer scheduledTimerWithTimeInterval: _interval target: self selector: @selector(countdown:) userInfo: nil repeats: YES];
}
}
- (void) stop {
if (_timer != nil) {
[_timer invalidate];
_timer = nil;
}
}
- (void) reset {
[self stop];
_value = _period;
if ((_delegate != nil) && [_delegate respondsToSelector: @selector(countdownTicker:didUpdateValue:withAction:)]) {
[_delegate countdownTicker: self didUpdateValue: _value withAction: ZIMCountdownTickerResetAction];
}
}
- (double) value {
[self stop];
return _value;
}
- (void) countdown: (NSTimer *)timer {
_value -= 1;
if ((_delegate != nil) && [_delegate respondsToSelector: @selector(countdownTicker:didUpdateValue:withAction:)]) {
[_delegate countdownTicker: self didUpdateValue: _value withAction: ZIMCountdownTickerTickAction];
}
if (_value <= 0) {
[self stop];
if ((_delegate != nil) && [_delegate respondsToSelector: @selector(countdownTickerDidFinish:)]) {
[_delegate countdownTickerDidFinish: self];
}
}
}
- (void) dealloc {
if (_delegate != nil) {
[_delegate release];
}
if (_timer != nil) {
[_timer invalidate];
}
[super dealloc];
}
@end
Look at NSTimer, it can most likely provide any needed timer functionality.
-(id) init
{
if( ! [super init] )
return nil;
// schedule timer
[self schedule: @selector(tick:)];
[self schedule: @selector(tick2:) interval:0.5];
return self;
}
-(void) tick: (ccTime) dt
{
//some function here
}
-(void) tick2: (ccTime) dt
{
//some function here
}