如何为cocos2d创建倒数计时器？

Question

我正在开发使用cocos2d的2D iPhone游戏。我需要一个倒数计时器。我如何在cocos2d中创建倒数计时器？

Answer 1

没有足够的代表处，以给予好评汤姆，但他是绝对正确的。在这个问题的背景下，NSTimer是错误的解决方案。 Cocos2d框架提供了一个与其他游戏功能集成的调度程序，如Pause/Resume（并且最有可能使用NSTimer）。从上述链接

实施例：

-(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 
} 

Answer 2

看看NSTimer，它很可能会提供任何所需的计时器功能。

NSTimer class reference

Answer 3

-(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 
} 

Answer 4

http://www.cocos2d-iphone.org/wiki/doku.php/prog_guide:best_practices

• 尝试不使用Cocoa的的NSTimer。而是使用cocos2d自己的调度程序。
• 如果你使用cocos2d的调度程序，你将有：
  • 自动暂停/恢复。
  • 当Layer（Scene，Sprite，CocosNode）进入舞台时，定时器会自动启动，当它离开舞台时，它会自动关闭。
  • 你的目标/选择器将与增量时间被称为...

Answer 5

在茯苓2d将有定时器缺省更新部。

试试这个：

[self schedule:@selector(update:)]; 
- (void)update:(ccTime)dt { 
} 

Answer 6

对于那些想使用的，而不是 “日程安排” 方法的NSTimer，你可以创建一个类，如下列：

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