How can I create a count down Timer for cocos2d ?

Question

Hello, I am developing a 2d iphone game by using cocos2d. I need a countdown timer. Plz tell me, How can I create a count down Timer in cocos2d ?

Answer 1

Look at NSTimer, it can most likely provide any needed timer functionality.

NSTimer class reference

Answer 2

Use NSTimer. It will call a method every x seconds (x specified when creating the timer) This example calls the method changeTime every 1 second

NSTimer *timer = [NSTimer scheduledTimerWithTimeInterval:1.0 target:self selector:@selector(changeTime:) userInfo:nil repeats:YES];

-(void)changeTime:(NSTimer *)theTimer{
if(timeLeft==0){
 return;
}
else{
 timeLeft = timeLeft - 1;
 if(timeLeft==0){
  [theTimer invalidate];
  [self goToNextExercise];
 }
}
label.text = [NSString stringWithFormat:@"%i",timeLeft];
}

Answer 3

http://code.google.com/p/cocos2d-iphone/wiki/BestPractices

Answer 4

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
}