UIPanGestureRecognizer UIScreenEdgePanGestureRecognizer

Configuring the Gesture Recognizer

@property(nonatomic) NSUInteger maximumNumberOfTouches//The maximum number of fingers that can be touching the view for this gesture to be recognized.
@property(nonatomic) NSUInteger minimumNumberOfTouches//The minimum number of fingers that can be touching the view for this gesture to be recognized.

Tracking the Location and Velocity of the Gesture

- (CGPoint)translationInView:(UIView *)view//The translation of the pan gesture in the coordinate system of the specified view.平移的距离。设置后速度为0.
- (void)setTranslation:(CGPoint)translation inView:(UIView *)view//设置平移的距离
- (CGPoint)velocityInView:(UIView *)view//速度。 which is expressed in points per second.

例子

方法1：

    CGFloat translationX = [pan translationInView:self.view].x;
    pan.view.center = CGPointMake(pan.view.center.x+translationX, pan.view.center.y);
    [pan setTranslation:CGPointZero inView:self.view];

方法2：

CGPoint translation = [recognizer translationInView:recognizer.view];

case UIGestureRecognizerStateBegan: {
            [recognizer setTranslation:CGPointMake(recognizer.view.frame.origin.x, 0) inView:recognizer.view];
            break;
        }
        case UIGestureRecognizerStateChanged: {
            [recognizer.view setTransform:CGAffineTransformMakeTranslation(MAX(0,translation.x), 0)];            
            [self statusBarView].transform = recognizer.view.transform;
            break;
        }

目前看来，translationInView的参数是attach的view还是其父view关系不大。每次的translation都是与上次的叠加。因此如果每次设置为0，则累加坐标即可。否则要用setTransform。

UIScreenEdgePanGestureRecognizer

A UIScreenEdgePanGestureRecognizer looks for panning (dragging) gestures that start near an edge of the screen. The system uses screen edge gestures in some cases to initiate view controller transitions. You can use this class to replicate the same gesture behavior for your own actions.

@property(readwrite, nonatomic, assign) UIRectEdge edges

The edges you specify are always relative to the app’s current interface orientation. This behavior ensures that the gestures always occur from the same place in your user interface, regardless of the device’s current orientation.

UIRectEdge的值如下：

typedef enum : NSUInteger  {
   UIRectEdgeNone    = 0,
   UIRectEdgeTop     = 1 << 0,
   UIRectEdgeLeft    = 1 << 1,
   UIRectEdgeBottom  = 1 << 2,
   UIRectEdgeRight   = 1 << 3,
   UIRectEdgeAll  = UIRectEdgeTop  | UIRectEdgeLeft  | UIRectEdgeBottom  | UIRectEdgeRight 
} UIRectEdge;