iOS仿抖音视频加载动画效果的实现方法

@interface ViewController ()@property (nonatomic, strong) UIView *playLoadingView;@end@implementation ViewController- (void)viewDidLoad { [super viewDidLoad];  //init player status bar self.playLoadingView = [[UIView alloc]init]; self.playLoadingView.backgroundColor = [UIColor whiteColor]; [self.playLoadingView setHidden:YES]; [self.view addSubview:self.playLoadingView];  //make constraintes [self.playLoadingView mas_makeConstraints:^(MASConstraintMaker *make) { make.center.equalTo(self.view); make.width.mas_equalTo(1.0f); //宽 1 dp make.height.mas_equalTo(0.5f); //高 0.5 dp }];  [self startLoadingPlayAnimation:YES]; //调用动画代码}

- (void)startLoadingPlayAnimation:(BOOL)isStart { if (isStart) { self.playLoadingView.backgroundColor = [UIColor whiteColor]; self.playLoadingView.hidden = NO; [self.playLoadingView.layer removeAllAnimations];  CAAnimationGroup *animationGroup = [[CAAnimationGroup alloc] init]; animationGroup.duration = 0.5; animationGroup.beginTime = CACurrentMediaTime() + 0.5; animationGroup.repeatCount = MAXFLOAT; animationGroup.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut];  CABasicAnimation *scaleAnimation = [CABasicAnimation animation]; scaleAnimation.keyPath = @"transform.scale.x"; scaleAnimation.fromValue = @(1.0f); scaleAnimation.toValue = @(1.0f * ScreenWidth);  CABasicAnimation *alphaAnimation = [CABasicAnimation animation]; alphaAnimation.keyPath = @"opacity"; alphaAnimation.fromValue = @(1.0f); alphaAnimation.toValue = @(0.5f);  [animationGroup setAnimations:@[scaleAnimation, alphaAnimation]]; [self.playLoadingView.layer addAnimation:animationGroup forKey:nil]; } else { [self.playLoadingView.layer removeAllAnimations]; self.playLoadingView.hidden = YES; }}

CABasicAnimation *scaleAnimation = [CABasicAnimation animation];scaleAnimation.keyPath = @"transform.scale.x";scaleAnimation.fromValue = @(1.0f);scaleAnimation.toValue = @(1.0f * ScreenWidth);