如何绘制UIImage或直接在-drawRect:中绘制？
我有一个 UIImage，我想在 UIView 上绘制它。但我不想创建 UIImageView 并将其添加为子视图，而是想覆盖 -drawRect: 并直接绘制我的 UIView。
例如，我的代码如下所示：
- (void)drawRect:(CGRect)rect {
CGContextRef myContext = UIGraphicsGetCurrentContext();
UIImage *img = [UIImage imageNamed:@"foo.png"];
// how to draw the directly into the view now?
}
I have an UIImage which I want to draw on a UIView. But instead of creating an UIImageView and adding this as a subview, I want to overwrite -drawRect: and draw my UIView directly.
For example, my code looks like:
- (void)drawRect:(CGRect)rect {
CGContextRef myContext = UIGraphicsGetCurrentContext();
UIImage *img = [UIImage imageNamed:@"foo.png"];
// how to draw the directly into the view now?
}
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调用
[img drawInRect:rect];。Call
[img drawInRect:rect];.顺便说一句，您不应该在 drawRect 方法中加载图像文件。因为每当视图需要更新时就会调用该方法。因此，它（当然是加载程序）在运行过程中可能会被调用很多次。
（此外，OS2.x的imageNamed方法有一个bug——没有缓存图像而泄露了图像。）
因此，你最好在初始化方法中加载文件，而不是在drawRect中。
BTW, you shouldn't load the image file in the drawRect method. Because the method is called whenever the view is required to update. Therefore, it (of course, loading procedure) may be called many many times during running.
(Furthermore, OS2.x's imageNamed method has a bug -- not cached the image and leaked it.)
Therefore, you'd better to load the file in the initialization method, not in the drawRect.