可以拖动的View

@interface BallView : UIView
{
CGPoint startPoint;
}
@end

@implementation BallView

- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event
{
// 获取触摸对象
UITouch *touch = [touches anyObject];
startPoint = [touch locationInView:self];
}

- (void)touchesMoved:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event
{
//获取触摸的对象
UITouch *touch = [touches anyObject];
CGPoint newPoint = [touch locationInView:self];
// 分别计算x y变动的距离
CGFloat dx = newPoint.x - startPoint.x;
CGFloat dy = newPoint.y - startPoint.y;

// 改变中心点坐标
self.center = CGPointMake(self.center.x + dx, self.center.y + dy);
}

@end

- (void)viewDidLoad {
[super viewDidLoad];

BallView *ball = [[BallView alloc] initWithFrame:CGRectMake(0, 0, 100, 100)];
ball.backgroundColor = [UIColor redColor];
ball.layer.cornerRadius = ball.frame.size.width / 2;
ball.layer.masksToBounds = YES;
[self.view addSubview:ball];
}