很久之前看过一篇讲CATransform3D的文章，现在找不到了...，这个效果是文章里面的，现在重新实现一下这个效果。

- (void)viewDidLoad {
    [super viewDidLoad];
    
    UIScrollView *scroll = [UIScrollView new];
    scroll.frame = [UIScreen mainScreen].bounds;
    scroll.backgroundColor = [UIColor blackColor];
    scroll.contentSize = CGSizeMake(scroll.bounds.size.width*3, scroll.bounds.size.width*3);
    [self.view addSubview:scroll];
    
    //设置父图层的sublayerTransform属性的m34值，那么所有的子图层都会生效，且共同享有一个灭点
    CATransform3D transform = CATransform3DIdentity;
    transform.m34 = -1.0 / 500;
    scroll.layer.sublayerTransform = transform;
    
    
    int row = 5;
    int col = 5;
    int level = 11;
    int wight = 50;
    int margin = 30;
    
    dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(3 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
        for (int i=0; i<row; i++) {   //行
            for (int j=0; j<col; j++) {   //列
                for (int k=0; k<level; k++) {   //层
                    CALayer *layer = [CALayer layer];

                    //设置背景色，越底部的图层颜色越深
                    CGFloat color = 0.2+k*(0.8/level);
                    layer.backgroundColor = [UIColor colorWithRed:color green:color blue:color alpha:1].CGColor;
                    layer.opaque = YES;
                    layer.frame = CGRectMake(200 + i*(margin+wight), 200 + j*(margin+wight), 50, 50);
                    CATransform3D transform = CATransform3DMakeTranslation(0, 0, k*50-150);
                    
                    //动画
                    CABasicAnimation *anim = [CABasicAnimation animation];
                    anim.fromValue = @(CATransform3DMakeTranslation(0, 0, 0));
                    anim.toValue = @(transform);
                    anim.duration = k*0.2;
                    anim.keyPath = @"transform";
                    anim.removedOnCompletion = NO;          //动画完成时不移除动画
                    anim.fillMode = kCAFillModeForwards;
                    
                    [layer addAnimation:anim forKey:@""];
                    [scroll.layer addSublayer:layer];
                }
            }
        }
    });
    
}