前言

今天跟大家分享的是抖音中或者快手中加載視頻的動(dòng)畫

上圖看成品

實(shí)現(xiàn)原理

首先我創(chuàng)建一個(gè)視圖

@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); //寬 1 dp
        make.height.mas_equalTo(0.5f); //高 0.5 dp
    }];

    [self startLoadingPlayAnimation:YES]; //調(diào)用動(dòng)畫代碼
}

這里我們可以看到 我們實(shí)際上創(chuàng)建的是一個(gè) 1pt寬度 0.5 pt的寬度 的視圖

緊接著動(dòng)畫實(shí)現(xiàn)的代碼

- (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;
    }
}

完事 就這幾行代碼 搞定

其實(shí)核心的只有4行代碼

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

關(guān)鍵在scaleAnimation.keyPath = @"transform.scale.x"; 這里我們要沿著x做縮放

縮放的得值從 1~屏幕寬度, 當(dāng)然值多大自己可以控制.

如果@"transform.scale.y" 則是沿著Y軸縮放

當(dāng)然 如果寫成@"transform.scale" 那就X,Y 一起縮放 大家可以試試.

總結(jié)

本篇的動(dòng)畫技巧是 縮放的 transform.scale.y 從一個(gè)點(diǎn) 做layer縮放 就會(huì)出現(xiàn) 加載效果.

如果需要抖音視頻加載動(dòng)畫 Demo，可以加iOS高級技術(shù)交流群：937194184阳距，獲取Demo,以及更多iOS學(xué)習(xí)資料

轉(zhuǎn)載：原文地址