iOS 悬浮可拖动可点击按钮

项目里下完单之后要悬浮红包，类似饿了吗那种。

做完了记录下：

@implementation SearchResultViewController

{

    UIButton  * moveRedPacket;

}

#pragma mark 红包

//创建移动红包的UI

-(void)CreatMoveRedPacketUI{

    

    UIPanGestureRecognizer   *  panTouch    =   [[UIPanGestureRecognizer 
alloc]initWithTarget:self
action:@selector(handlePan:)];

    if (moveRedPacket==nil) {

        moveRedPacket =   [[UIButton 
alloc]initWithFrame:CGRectMake(ScreenWidth-120,
ScreenHeight-120,
80, 85)];

    }

    [moveRedPacket
setBackgroundImage:[UIImage
imageNamed:@"red"]
forState:UIControlStateNormal];

    [moveRedPacket
addTarget:self
action:@selector(ClickRedPacket:)
forControlEvents:UIControlEventTouchUpInside];

    [moveRedPacket
addGestureRecognizer:panTouch];

    [self.view 
addSubview:moveRedPacket];

    

}

/**

 *  处理拖动手势

 *

 *  @param recognizer 拖动手势识别器对象实例

 */

- (void)handlePan:(UIPanGestureRecognizer *)recognizer {

    //视图前置操作

    [recognizer.view.superview
bringSubviewToFront:recognizer.view];

    

    CGPoint center = recognizer.view.center;

    CGFloat cornerRadius = recognizer.view.frame.size.width
/ 2;

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

    //NSLog(@"%@", NSStringFromCGPoint(translation));

    recognizer.view.center =
CGPointMake(center.x + translation.x, center.y
+ translation.y);

    [recognizer setTranslation:CGPointZero
inView:self.view];

    

    if (recognizer.state ==
UIGestureRecognizerStateEnded) {

       
//计算速度向量的长度，当他小于200时，滑行会很短

        CGPoint velocity = [recognizer
velocityInView:self.view];

        CGFloat magnitude =
sqrtf((velocity.x * velocity.x) + (velocity.y
* velocity.y));

        CGFloat slideMult = magnitude /
200;

        //NSLog(@"magnitude: %f, slideMult: %f", magnitude, slideMult); //e.g. 397.973175, slideMult: 1.989866

        

       
//基于速度和速度因素计算一个终点

        float slideFactor =
0.1 * slideMult;

        CGPoint finalPoint =
CGPointMake(center.x + (velocity.x * slideFactor),

                                         center.y + (velocity.y * slideFactor));

        //限制最小［cornerRadius］和最大边界值［self.view.bounds.size.width
- cornerRadius］，以免拖动出屏幕界限

        finalPoint.x =
MIN(MAX(finalPoint.x, cornerRadius),

                           self.view.bounds.size.width
- cornerRadius);

        finalPoint.y =
MIN(MAX(finalPoint.y, cornerRadius),

                           self.view.bounds.size.height
- cornerRadius);

        

        //使用 UIView
动画使 view
滑行到终点

        [UIView
animateWithDuration:slideFactor*2

                              delay:0

                            options:UIViewAnimationOptionCurveEaseOut

                         animations:^{

                             recognizer.view.center = finalPoint;

                         }

                         completion:nil];

    }

}