UIButton文字对齐与手势长按执行两次的问题

UIButton文字对齐：

   调用按钮中的titillabel来者是文字的对齐时无效的需要调用UIView中的方法，方法如下：

    @property(nonatomic) UIControlContentVerticalAlignment contentVerticalAlignment; // how to position content vertically inside control. default is center
@property(nonatomic) UIControlContentHorizontalAlignment contentHorizontalAlignment; // how to position content hozontally inside control. default is center

手势长按执行两次问题：
  手势在进行长按时会由几种状态，要对每种状态进行处理，根据需要咯，几种状态如下：

 typedef NS_ENUM(NSInteger, UIGestureRecognizerState) {
UIGestureRecognizerStatePossible, // the recognizer has not yet recognized its gesture, but may be evaluating touch events. this is the default state

UIGestureRecognizerStateBegan, // the recognizer has received touches recognized as the gesture. the action method will be called at the next turn of the run loop
UIGestureRecognizerStateChanged, // the recognizer has received touches recognized as a change to the gesture. the action method will be called at the next turn of the run loop
UIGestureRecognizerStateEnded, // the recognizer has received touches recognized as the end of the gesture. the action method will be called at the next turn of the run loop and the recognizer will be reset to UIGestureRecognizerStatePossible
UIGestureRecognizerStateCancelled, // the recognizer has received touches resulting in the cancellation of the gesture. the action method will be called at the next turn of the run loop. the recognizer will be reset to UIGestureRecognizerStatePossible

UIGestureRecognizerStateFailed, // the recognizer has received a touch sequence that can not be recognized as the gesture. the action method will not be called and the recognizer will be reset to UIGestureRecognizerStatePossible

// Discrete Gestures – gesture recognizers that recognize a discrete event but do not report changes (for example, a tap) do not transition through the Began and Changed states and can not fail or be cancelled
UIGestureRecognizerStateRecognized = UIGestureRecognizerStateEnded // the recognizer has received touches recognized as the gesture. the action method will be called at the next turn of the run loop and the recognizer will be reset to UIGestureRecognizerStatePossible
};

对应UIGestureRecognizer中的state属性。