不妨粘贴代码以防万一有人尝试为具有自己的内部绘制例程的堆叠 CALayer 设置动画
- (void)drawRect:(CGRect)rect {
[imgLayer removeFromSuperlayer];
CGFloat w = [self.blockViewDelegate w];
CGFloat h = [self.blockViewDelegate h];
CGFloat wb = w/4;
CGFloat hb = h/4;
CGContextRef viewContext = UIGraphicsGetCurrentContext();
// Layers
[bottomLayer sizes:wb :hb :1];
bottomLayer.frame = CGRectMake(0, 0, w, h);
bottomLayer.opaque = NO;
[topLayer sizes:wb :hb :0];
topLayer.frame = CGRectMake(0, 0, w, h);
topLayer.opaque = NO;
// Overlay
imgLayer.frame = CGRectMake(0, 0, w, h);
imgLayer.opaque = NO;
imgLayer.opacity = 1.0f;
UIImage *overlay = [self.blockViewDelegate image];
CGImageRef img = overlay.CGImage;
imgLayer.contents = (id)img;
// Add layers
[bottomLayer drawInContext:viewContext];
[topLayer drawInContext:viewContext];
[self.layer addSublayer:imgLayer];
}
blockViewDelegate 是我存储宽度、高度和图像信息的地方,它是这个 UIView 的控制器。
topLayer 和 bottomLayer 是自定义 UIView 子类,它们在视图中绘制一些具有可变颜色信息的形状。稍后在我的动画中,我只是用计时器重复运行“setNeedsDisplay”,这个例程重复,层使用更新的参数重新绘制。