iOS中利用CoreAnimation实现一个时间的进度条效果

 然后呢，需要在动画的delegate与暂停、恢复动画的方法中分别修改动画的状态

- (void)pauseAnimation
{
 CFTimeInterval pausedTime = [self convertTime:CACurrentMediaTime() fromLayer:nil];
 self.speed = 0.0;
 self.timeOffset = pausedTime;
 self.animatingStatus = WKAnimationStatusPause;
}
- (void)resumeAnimation
{
 CFTimeInterval pausedTime = [self timeOffset];
 self.speed = 1.0;
 self.timeOffset = 0.0;
 self.beginTime = 0.0;
 CFTimeInterval timeSincePause = [self convertTime:CACurrentMediaTime() fromLayer:nil] - pausedTime;
 self.beginTime = timeSincePause;
 self.animatingStatus = WKAnimationStatusAnimating;
}
#pragma mark - CAAnimationDelegate
/* Called when the animation begins its active duration. */
- (void)animationDidStart:(CAAnimation *)anim
{
 if (anim == [self animationForKey:@"progressAnimation"]) {//判断进度动画
  self.animatingStatus = WKAnimationStatusAnimating;
 }
}
- (void)animationDidStop:(CAAnimation *)anim finished:(BOOL)flag
{
 if ([anim valueForKey:@"progress"] && flag == YES) {//判断进度动画
  self.animatingStatus = WKAnimationStatusComplete;
 }
}

- (void)viewDidLoad {
 [super viewDidLoad];
  
 WKProgressBarLayer *progressLayer = [[WKProgressBarLayer alloc] init];
 progressLayer.frame = CGRectMake(100, 100, 200, 10);
  
 [self.view.layer addSublayer:progressLayer];
  
 self.progressLayer = progressLayer;
}

- (IBAction)startOrPauseAction:(UIButton *)sender {
  switch (self.progressLayer.animatingStatus) {
   case WKAnimationStatusIdle:{
    [self.progressLayer beginAnimationWithDuration:10];
   }
    break;
   case WKAnimationStatusAnimating:{
    [self.progressLayer pauseAnimation];
   }
    break;
   case WKAnimationStatusPause:{
    [self.progressLayer resumeAnimation];
   }
    break;
   case WKAnimationStatusComplete:{
    [self.progressLayer restartAnimationWithProgress:0 duration:10];
   }
    break;
   default:
    break;
 }
 sender.selected = !sender.selected;
}
- (IBAction)resetAction:(UIButton *)sender {
 [self.progressLayer restartAnimationWithProgress:0 duration:10];
 self.startOrPauseButton.selected = YES;
}