UIControlState

typedef NS_OPTIONS(NSUInteger, UIControlState) {
    UIControlStateNormal       = 0,						//控件的正常或默认状态 ,即已启用但未选中也未突出显示
    UIControlStateHighlighted  = 1 << 0,                  // used when UIControl isHighlighted is set 突出显示控件的状态 俗称高亮
    UIControlStateDisabled     = 1 << 1,				//禁用控件状态
    UIControlStateSelected     = 1 << 2,                  // flag usable by app (see below)选择控件的状态
    UIControlStateFocused NS_ENUM_AVAILABLE_IOS(9_0) = 1 << 3, // Applicable only when the screen supports focus获得焦点状态
    UIControlStateApplication  = 0x00FF0000,              // additional flags available for application use附加的控制状态标志可供应用程序使用
    UIControlStateReserved     = 0xFF000000               // flags reserved for internal framework use内部框架使用保留的控制状态
};