UIButton

按钮类型

按钮的类型定义其基本外观和行为。创建按钮后，你无法更改其类型。最常用的按钮类型是自定义和系统类型，但在适当时使用其他类型

• UIButtonTypeCustom

  No button style.
  

• UIButtonTypeSystem

  A system style button, such as those shown in navigation bars and toolbars.
  

• UIButtonTypeDetailDisclosure

  A detail disclosure button.
  

• UIButtonTypeInfoLight

  An information button that has a light background.
  

• UIButtonTypeInfoDark

  An information button that has a dark background.
  

• UIButtonTypeContactAdd

  A contact add button.
  

创建自定义按钮（即自定义类型的按钮）时，按钮的框架最初设置为（0,0,0,0）。在将按钮添加到界面之前，应将帧更新为更合适的值。