- (void)viewDidLoad {
? ? [super viewDidLoad];
? ? Width=[UIScreen mainScreen].bounds.size.width;
? ? Height=[UIScreen mainScreen].bounds.size.height;
? ??
? ? UIButton *btn=[[UIButton alloc]initWithFrame:CGRectMake(10, 200, 60, 60)];
? ? btn.backgroundColor=[UIColor blueColor];
? ? [btn setTitle:@"B" forState:UIControlStateNormal];
? ? //UIPanGestureRecognizer手勢
? ? UIPanGestureRecognizer *pan=[[UIPanGestureRecognizer alloc]initWithTarget:self action:@selector(movingBtn:)];
? ? [btn addGestureRecognizer:pan];
? ??
? ? [self.view addSubview:btn];
? ??
}

-(void)movingBtn:(UIPanGestureRecognizer *)recognizer{
? ? //得到拖拽的UIButton
? ? UIButton *button = (UIButton *)recognizer.view;
? ? //得到拖拽的偏移量
? ? CGPoint translation = [recognizer translationInView:button];
? ??
? ? //對拖拽事件的狀態(tài)進行判斷 也就是選擇自定義手勢的原因
? ? if(recognizer.state == UIGestureRecognizerStateBegan){
? ? ? ??
? ? }else if(recognizer.state == UIGestureRecognizerStateChanged){
? ? ? ? //實時設置button的center、recognizer
? ? ? ? button.center = CGPointMake(button.center.x + translation.x, button.center.y + translation.y);
? ? ? ? [recognizer setTranslation:CGPointZero inView:button];
?
? ? ? ? //對button的位置進行判斷，超出范圍則強行使拖拽事件結束
? ? ? ? //這個范圍可以自己自定義
? ? ? ? if(button.center.x <= 40 || button.center.x>=Width-40 || button.center.y <=100 || button.center.y >=Height-100){
? ? ? ? ? ? [recognizer setState:UIGestureRecognizerStateEnded];
? ? ? ? }
? ? ? ??
? ? }else if(recognizer.state == UIGestureRecognizerStateEnded){
? ? ? ? //得到結束時button的center
? ? ? ? //根據(jù)center 判斷應該的X和Y
? ? ? ? CGFloat newX=button.center.x;
? ? ? ? if(button.center.x <=Width/2) newX=40;
? ? ? ? else if(button.center.x >=Width/2) newX=Width-40;
? ? ? ??
? ? ? ? CGFloat newY=button.center.y;
? ? ? ? if(button.center.y <=100) newY=100;
? ? ? ? else if(button.center.y >=Height-100) newY=Height-100;
? ? ? ??
? ? ? ? button.center = CGPointMake(newX, newY);
? ? ? ? [recognizer setTranslation:CGPointZero inView:button];
? ? }
}