例如要獲取的控件是Lable, 則可使用下面方法獲取該視圖相對屏幕的位置:
UIWindow * window=[[[UIApplication sharedApplication] delegate] window];
CGRect startRact = [Lable convertRect:Lable.bounds toView:window];
UIWindow * window=[[[UIApplication sharedApplication] delegate] window];
CGRect startRact = [Lable convertRect:Lable.bounds toView:window];