用代码给控件添加事件

[pagectrl addTarget:self action:@selector(<span style="color:#FF0000;">pageTuring:</span>) forControlEvents:UIControlEventValueChanged];

pagectrl 是控件

<span style="color:#FF0000;">pageTuring: <span style="color:#000000;">就是事件处理函数，它一定要在</span></span>addTarget语句 执行前 先声明或定义

forControlEvents 是想要注册的事件类型
<pre name="code" class="objc">typedef NS_OPTIONS(NSUInteger, UIControlEvents) {
UIControlEventTouchDown           = 1 <<  0,      // on all touch downs
UIControlEventTouchDownRepeat     = 1 <<  1,      // on multiple touchdowns (tap count > 1)
UIControlEventTouchDragInside     = 1 <<  2,
UIControlEventTouchDragOutside    = 1 <<  3,
UIControlEventTouchDragEnter      = 1 <<  4,
UIControlEventTouchDragExit       = 1 <<  5,
UIControlEventTouchUpInside       = 1 <<  6,
UIControlEventTouchUpOutside      = 1 <<  7,
UIControlEventTouchCancel         = 1 <<  8,

UIControlEventValueChanged        = 1 << 12,     // sliders, etc.

UIControlEventEditingDidBegin     = 1 << 16,     // UITextField
UIControlEventEditingChanged      = 1 << 17,
UIControlEventEditingDidEnd       = 1 << 18,
UIControlEventEditingDidEndOnExit = 1 << 19,     // 'return key' ending editing

UIControlEventAllTouchEvents      = 0x00000FFF,  // for touch events
UIControlEventAllEditingEvents    = 0x000F0000,  // for UITextField
UIControlEventApplicationReserved = 0x0F000000,  // range available for application use
UIControlEventSystemReserved      = 0xF0000000,  // range reserved for internal framework use
UIControlEventAllEvents           = 0xFFFFFFFF
};