iOS 启动页放大淡出效果

//屏幕宽度
#define kWIDTH [UIScreen mainScreen].bounds.size.width
//屏幕高度

#define kHEIGHT [UIScreen mainScreen].bounds.size.height

UIImageView * lunchImg=[[UIImageView alloc]initWithFrame:CGRectMake(0, 0, WIDTH, HEIGHT)];
        lunchImg.image=[UIImage imageNamed:@"lunch"];
        [[UIApplication sharedApplication].keyWindow addSubview:lunchImg];


        [UIView animateWithDuration:0.8 animations:^{
            lunchImg.layer.transform = CATransform3DMakeScale(1.5, 1.5, 1);
            lunchImg.alpha=0.0;
        } completion:^(BOOL finished) {
            [lunchImg removeFromSuperview];
        }];