我正在尝试开发过渡效果,当一个视图分成两个部分时,上半部分向上动画,下半部分向下动画,以揭示其后面的视图。 我使用UIView和UIImageView方法来实现:
// 1. Make a screenshot:
UIGraphicsBeginImageContext(parentView.frame.size);
[parentView.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *screenshot = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
// 2. Calculate rectangles for top and bottom part:
CGRect rectTop, rectBottom;
CGFloat W = rectBig.size.width;
CGFloat H = rectBig.size.height;
rectTop = CGRectMake(0, 0, W, y_cutoff);
rectBottom = CGRectMake(0, y_cutoff, W, H - y_cutoff);
// 3. Create top and bottom images:
CGImageRef imageRefTop = CGImageCreateWithImageInRect([screenshot CGImage], rectTop);
CGImageRef imageRefBottom = CGImageCreateWithImageInRect([screenshot CGImage], rectBottom);
UIImage *imageTop = [UIImage imageWithCGImage:imageRefTop];
UIImage *imageBottom = [UIImage imageWithCGImage:imageRefBottom];
// 4. Assign images to image views:
imageViewTop.image = imageTop;
imageViewBottom.image = imageBottom;
// 5. Animate image views:
[UIView beginAnimation:nil context:NULL];
.... animation code here
[UIView commitAnimations];
然而,这段代码在设备上非常缓慢,我相信有更有效的方法来实现这样的转换。很可能使用CALayers等方式实现。 你能指导我正确的方向吗?