CCDirector.m

#pragma mark -
#pragma mark DisplayLinkDirector

// Allows building DisplayLinkDirector for pre-3.1 SDKS
// without getting compiler warnings.
@interface NSObject(CADisplayLink)

+ (id) displayLinkWithTarget:(id)arg1 selector:(SEL)arg2;
- (void) addToRunLoop:(id)arg1 forMode:(id)arg2;
- (void) setFrameInterval:(int)interval;
- (void) invalidate;

@end

@implementation CCDisplayLinkDirector

- (void)setAnimationInterval:(NSTimeInterval)interval
{
	animationInterval = interval;
	if(displayLink){
		[self stopAnimation];
		[self startAnimation];
	}
}

- (void) startAnimation
{
	if ( gettimeofday( &lastUpdate, NULL) != 0 ) {
		CCLOG(@"cocos2d: DisplayLinkDirector: Error on gettimeofday");
	}
	
	// approximate frame rate
	// assumes device refreshes at 60 fps
	int frameInterval	= (int) floor(animationInterval * 60.0f);
	
	CCLOG(@"cocos2d: Frame interval: %d", frameInterval);

	displayLink = [NSClassFromString(@"CADisplayLink") displayLinkWithTarget:self selector:@selector(preMainLoop:)];
	[displayLink setFrameInterval:frameInterval];
	[displayLink addToRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];
}

-(void) preMainLoop:(id)sender
{
	[self mainLoop];
}

- (void) stopAnimation
{
	[displayLink invalidate];
	displayLink = nil;
}

-(void) dealloc
{
	[displayLink release];
	[super dealloc];
}
@end