需求

在一个app应用的最顶部添加一个悬浮窗，就像ios系统AssistiveTouch 可以左右滑动，但是最终会停在左边或右边。

实现思路

在应用的视图的最顶层添加一个UIWindow，用这个UIWindow 充当悬浮窗，给UIWindow添加移动的手势监听，让悬浮窗随着手指移动，释放的时候，让它以动画的方式靠边

代码

    //悬浮窗测试//创建一个悬浮窗口mwindow = [[AssistiveTouch alloc]initWithFrame:CGRectMake(100, 200, 40, 40) imageName:@"1.png"];//ios9 window要设置rootview 不然崩溃UIViewController *controller = [[UIViewController alloc] init];mwindow.rootViewController = controller;//展示悬浮窗。。[self.window makeKeyAndVisible];

        //添加移动的手势UIPanGestureRecognizer *pan = [[UIPanGestureRecognizer alloc]initWithTarget:self action:@selector(locationChange:)];pan.delaysTouchesBegan = YES;[self addGestureRecognizer:pan];

//改变位置
-(void)locationChange:(UIPanGestureRecognizer*)p
{//[[UIApplication sharedApplication] keyWindow]CGPoint panPoint = [p locationInView:[[UIApplication sharedApplication] keyWindow]];if(p.state == UIGestureRecognizerStateBegan){[NSObject cancelPreviousPerformRequestsWithTarget:self selector:@selector(changeColor) object:nil];_imageView.alpha = 0.8;}else if (p.state == UIGestureRecognizerStateEnded){[self performSelector:@selector(changeColor) withObject:nil afterDelay:4.0];}if(p.state == UIGestureRecognizerStateChanged){self.center = CGPointMake(panPoint.x, panPoint.y);}else if(p.state == UIGestureRecognizerStateEnded){if(panPoint.x <= kScreenWidth/2){if(panPoint.y <= 40+HEIGHT/2 && panPoint.x >= 20+WIDTH/2){[UIView animateWithDuration:0.2 animations:^{self.center = CGPointMake(panPoint.x, HEIGHT/2);}];}else if(panPoint.y >= kScreenHeight-HEIGHT/2-40 && panPoint.x >= 20+WIDTH/2){[UIView animateWithDuration:0.2 animations:^{self.center = CGPointMake(panPoint.x, kScreenHeight-HEIGHT/2);}];}else if (panPoint.x < WIDTH/2+15 && panPoint.y > kScreenHeight-HEIGHT/2){[UIView animateWithDuration:0.2 animations:^{self.center = CGPointMake(WIDTH/2, kScreenHeight-HEIGHT/2);}];}else{CGFloat pointy = panPoint.y < HEIGHT/2 ? HEIGHT/2 :panPoint.y;[UIView animateWithDuration:0.2 animations:^{self.center = CGPointMake(WIDTH/2, pointy);}];}}else if(panPoint.x > kScreenWidth/2){if(panPoint.y <= 40+HEIGHT/2 && panPoint.x < kScreenWidth-WIDTH/2-20 ){[UIView animateWithDuration:0.2 animations:^{self.center = CGPointMake(panPoint.x, HEIGHT/2);}];}else if(panPoint.y >= kScreenHeight-40-HEIGHT/2 && panPoint.x < kScreenWidth-WIDTH/2-20){[UIView animateWithDuration:0.2 animations:^{self.center = CGPointMake(panPoint.x, 480-HEIGHT/2);}];}else if (panPoint.x > kScreenWidth-WIDTH/2-15 && panPoint.y < HEIGHT/2){[UIView animateWithDuration:0.2 animations:^{self.center = CGPointMake(kScreenWidth-WIDTH/2, HEIGHT/2);}];}else{CGFloat pointy = panPoint.y > kScreenHeight-HEIGHT/2 ? kScreenHeight-HEIGHT/2 :panPoint.y;[UIView animateWithDuration:0.2 animations:^{self.center = CGPointMake(320-WIDTH/2, pointy);}];}}}
}