最近因為需要，做了下嗶哩嗶哩動畫這個應(yīng)用。從數(shù)據(jù)、素材的抓取、分類、測試，到應(yīng)用的基本功能實現(xiàn)，確實用了一段時間。下面是做嗶哩嗶哩動畫的開機動畫效果的實現(xiàn)。

![Uploading LuanchImage設(shè)置_552569.png . . .]](http://upload-images.jianshu.io/upload_images/2023147-b27b7518b9e7f8c7.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240)

動畫開機圖.png

從圖一到圖二，中間的人物從小到大，從透明到呈現(xiàn)的過程。
實現(xiàn)這個效果并不難，步驟如下
1.在LuanchImage設(shè)置開機圖片

LuanchImage設(shè)置.png

LuanchImage.png

2.使用CABasicAnimationGroup實現(xiàn)動畫效果
這里創(chuàng)建了一個視圖控制器類LaunchViewController，用于實現(xiàn)動畫效果。
設(shè)置兩個屬性，其中bgImageView是背景圖，playImageView是做動畫的圖片。

@property (nonatomic,strong)UIImageView  *bgImageView;
@property (nonatomic,strong)UIImageView  *playImageView;

給這兩個屬性懶加載

- (UIImageView *)bgImageView{
   
   if(!_bgImageView){
       _bgImageView = [[UIImageView alloc] initWithFrame:CGRectMake(0, 0, ScreenWidth, ScreenHeight)];
       _bgImageView.image = [UIImage imageNamed:@"bilibili_splash_iphone_bg"];
   }
   return _bgImageView;
}

- (UIImageView *)playImageView{
   
   if(!_playImageView){
       _playImageView = [[UIImageView alloc] initWithFrame:CGRectMake(ScreenWidth/2, ScreenHeight/2-100, 1, 1.3)];
       _playImageView.image = [UIImage imageNamed:@"bilibili_splash_default"];
   }
   return _playImageView;
}

在viewDidLoad中把視圖添加上去

    [self.view addSubview:self.bgImageView];
    [self.bgImageView addSubview:self.playImageView];
    [self performSelector:@selector(animationLunch) withObject:self afterDelay:0];

animationLunch中實現(xiàn)組合動畫效果

- (void)animationLunch{
    
    CGFloat duration = 1.5;
    CABasicAnimation *scale = [CABasicAnimation animationWithKeyPath:@"transform.scale"];
    scale.fromValue = @1;
    scale.toValue = @(ScreenWidth - 40);
    scale.duration = duration;
    scale.repeatCount = 1;
    scale.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionLinear];
    
    CABasicAnimation *opacity = [CABasicAnimation animationWithKeyPath:@"opacity"];
    opacity.fromValue = @0;
    opacity.toValue = @1;
    opacity.duration = duration;
    scale.repeatCount = 1;
    
    CAAnimationGroup *animationGroup = [CAAnimationGroup animation];
    animationGroup.animations = @[scale,opacity];
    animationGroup.duration = duration;
    animationGroup.repeatCount = 1;
    //如果是一個動畫CAAnimation,則需要將其removedOnCompletion設(shè)置為NO,要不然fillMode不起作用
    animationGroup.removedOnCompletion = NO;
    //決定當(dāng)前在非active時間段的行為,比如動畫開始之前,動畫結(jié)束之后
    animationGroup.fillMode =kCAFillModeForwards;
    animationGroup.delegate = self;
    [self.playImageView.layer addAnimation:animationGroup forKey:nil];
}

讓LaunchViewController遵循代理，并實現(xiàn)CAAnimationDelegate協(xié)議

- (void)animationDidStop:(CAAnimation *)anim finished:(BOOL)flag{
    [NSThread sleepForTimeInterval:2.0];
    //移除開機動畫
    [self.bgImageView removeFromSuperview];
}

這個類要做的事情完成了，回到AppDelegate中，導(dǎo)入剛創(chuàng)建的類頭文件，在application: didFinishLaunchingWithOptions:中加入以下代碼,把動畫添加到場景中

  _launchVC = [[LaunchViewController alloc] init];
    //添加到場景
    [self.window addSubview:_launchVC.view];
    //放到最頂層
    [self.window bringSubviewToFront:_launchVC.view];
    [self performSelector:@selector(removeLunch) withObject:self afterDelay:2.0];

到此，嗶哩嗶哩動畫的開機動畫效果就實現(xiàn)了。