UIEdgeInsets

UIEdgeInsets  设置边距

UIEdgeInsets UIEdgeInsetsMake (

   CGFloat top,

   CGFloat left,

   CGFloat bottom,

   CGFloat right

);

按钮button中自带有一个label，通过设置label的边距可以自定义label在按钮中的位置：

[button  setTitleEdgeInsets:UIEdgeInsetsMake(0,0,0，0)];

设置按钮自带的label显示在按钮的右方（右对齐）

[button setContentHorizontalAlignment:UIControlContentHorizontalAlignmentRight];