Preface
I’ve spent the past few days wrestling with the open-source TikTok (Douyin) demo. Today I’m sharing the video loading animation used in TikTok or Kuaishou.
Here’s the finished result:
How It Works
First, I create a view:
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@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
}
As you can see, what we actually create is a view 1 pt wide and 0.5 pt tall.
Next, the animation implementation code:
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- (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;
}
}
That’s it — just those few lines and you’re done.
Actually, the core is only 4 lines of code:
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CABasicAnimation *scaleAnimation = [CABasicAnimation animation];
scaleAnimation.keyPath = @"transform.scale.x";
scaleAnimation.fromValue = @(1.0f);
scaleAnimation.toValue = @(1.0f * ScreenWidth);
The key is
scaleAnimation.keyPath = @"transform.scale.x";— here we want to scale along the x-axis.
The scale value goes from 1 to screen width — of course, you can control how large the value gets.
If you use @"transform.scale.y", it scales along the Y-axis.
And if you write @"transform.scale", it scales on both X and Y — give it a try.
Summary
The animation technique in this post is scaling via transform.scale.y: scaling the layer from a single point produces the loading effect.
Thanks for your support