利用CoreAnimation实现一个时间的进度条

(个人原创，转载请注明出处 http://www.cnblogs.com/pretty-guy/p/7460334.html)
在iOS中实现进度条通常都是通过不停的设置progress来完成的，这样的进度条适用于网络加载（上传下载文件、图片等）。但是对于录制视频这样的需求的话，如果是按照每秒来设置进度的话，显得有点麻烦，于是我就想直接用CoreAnimation来按时间做动画，只要设置最大时间，其他的就不用管了，然后在视频暂停与继续录制时，对动画进行暂停和恢复即可。录制视频的效果如下：



你可以在这里下载demo

那么接下来就是如何用CoreAnimation实现一个进度条控件了。

首先呢，让我们创建一个继承自CAShapeLayer的WKProgressBarLayer。

WKProgressBarLayer默认自身的bounds就是整个进度条的大小。

@interface WKProgressBarLayer : CAShapeLayer

@end

 为了方便外部调用，首先在WKProgressBarLayer.h中定义枚举来表明动画的四个状态

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

 接下来，定义外部调用的动画接口

@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

 然后，我们在.m实现核心的动画开始方法startAnimtionWithBeginProgress:duration:，详细解释见代码

- (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;
}

 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;
}
}

 至此，进度条layer就完成了，现在创建一个控制器来做测试

首先在storyBoard摆上两个按钮，分别是开始与重置动画(界面搭建很简单，详情见demo)

然后在ViewDidLoad中添加progressLayer

- (void)viewDidLoad {
[super viewDidLoad];

WKProgressBarLayer *progressLayer = [[WKProgressBarLayer alloc] init];
progressLayer.frame = CGRectMake(100, 100, 200, 10);

[self.view.layer addSublayer:progressLayer];

self.progressLayer = progressLayer;
}

 接下来，就是动画开始与重置响应

- (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;
}

 以上就是代码主体了，接下来，让我们看看效果



你可以在这里下载demo

 

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