iOS中利用CoreAnimation实现一个时间的进度条效果

@interface WKProgressBarLayer : CAShapeLayer
@end

typedef NS_ENUM(NSInteger, WKAnimationStatus) {
 WKAnimationStatusIdle,//空闲
 WKAnimationStatusAnimating,//动画中
 WKAnimationStatusPause,//暂停
 WKAnimationStatusComplete//完成
};

@interface WKProgressBarLayer : CAShapeLayer
@property (nonatomic, assign, readonly) WKAnimationStatus animatingStatus;//状态
/**
 开始动画
 @param duration 动画最大时长
 */
- (void)beginAnimationWithDuration:(CGFloat)duration;
/**
 暂停
 */
- (void)pauseAnimation;
/**
 恢复
 */
- (void)resumeAnimation;
/**
 重新开始动画
 @param progress 从哪个进度开始
 @param duration 动画最大时长
 */
- (void)restartAnimationWithProgress:(CGFloat)progress duration:(NSTimeInterval)duration;
@end

- (void)startAnimtionWithBeginProgress:(CGFloat)beginProgress duration:(NSTimeInterval)duration
{
 [self reset];//重置动画
 //设置path
 UIBezierPath *fromPath = [UIBezierPath bezierPathWithRect:CGRectMake(0, 0, beginProgress * self.bounds.size.width, self.bounds.size.height)];;
 UIBezierPath *toPath = [UIBezierPath bezierPathWithRect:self.bounds];
 self.path = fromPath.CGPath;
 //创建动画
 CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:@"path"];
 animation.fromValue = (id)fromPath.CGPath;
 animation.toValue = (id)toPath.CGPath;
 animation.duration = duration;
 [animation setValue:@1 forKey:@"progress"];//用于判断是否是进度动画
 animation.delegate = self; //用于判断动画结束
 [self addAnimation:animation forKey:@"progressAnimation"];
 self.path = toPath.CGPath;
}

- (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;
}