回滚绘制矩形：
有没有办法在不刷新当前UIView的情况下退出drawRect:？ 例如：
- (void)drawRect:(CGRect)rect {
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetRGBStrokeColor(context, 1.0, 1.0, 1.0, 1.0);
CGContextSetLineWidth(context, 2);
CGContextMoveToPoint(context, 10.0, 30.0);
CGContextAddLineToPoint(context, 310.0, 30.0);
CGContextStrokePath(context);
//I would like to return from here and rollback all changes in drawRect:
}
谢谢！
Is there any way to quit from drawRect: without refresh the current UIView?
For example:
- (void)drawRect:(CGRect)rect {
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetRGBStrokeColor(context, 1.0, 1.0, 1.0, 1.0);
CGContextSetLineWidth(context, 2);
CGContextMoveToPoint(context, 10.0, 30.0);
CGContextAddLineToPoint(context, 310.0, 30.0);
CGContextStrokePath(context);
//I would like to return from here and rollback all changes in drawRect:
}
Thanks!
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如果您还没有开始在上下文中绘图，则可能只从
drawRect:返回。之前您必须将视图的clearsContextBeforeDrawing属性设置为 NO。在上下文中开始绘制后，视图/图层将始终更新其内容。
If you haven't started drawing into the context, it might be possible to just return from
drawRect:. You'd have to set theclearsContextBeforeDrawingproperty of the view to NO before.After starting to draw in the context, the view/layer will always update its content.