UIEdgeInsets [objc]  typedef struct UIEdgeInsets {   CGFloat top, left, bottom, right;  // specify amount to inset (positive) for each of the edges. values can be negative to 'outset'   }

iOS 的控件，只看到  UIButton 可以设置Padding/Insets，即按钮上文字或图片与按钮边界的间隙，对与 CSS 来说叫做Padding，在 iOS 中叫做 Insets，UIButton 设置 Insets 相应的属性如下： Configuring Edge Insets      contentEdgeInsets  property      titleEdgeI