你如何初始化UIGestureRecognizer？

Question

我想在我的按钮上添加一个手势识别器,以便我可以在用户滑过按钮框架时运行代码.如果滑动向上,向右,向左或向下按钮,我也希望此代码不同.

-(void)viewDidLoad
{
    [super viewDidLoad];
    UIButton *button=[UIButton buttonWithType:UIButtonTypeRoundedRect];
    button.frame=CGRectMake(0, 0, 100, 100);
    [self.view addSubview:button];
    UIGestureRecognizer *swipe=[[UIGestureRecognizer alloc]initWithTarget:button action:@selector(detectSwipe)];
    [button addGestureRecognizer:swipe];
}

所以,我做的initWithTarget:action:事情是否正确？现在,我这样做我如何实施该detectSwipe方法？

这是我对如何实施的想法 detectSwipe

          -(IBAction)detectSwipe:(UIButton *)sender
        {
      /* I dont know how to put this in code but i would need something like, 
if (the swipe direction is forward and the swipe is > sender.frame ){ 
[self ForwardSwipeMethod];
    } else if //same thing for right
    else if //same thing for left
    else if //same thing for down

        }

Answer 1

不,这不对.手势识别器的目标不是按钮,它是在检测到手势时调用动作方法的对象(否则它将如何知道哪个对象调用该方法？在OO中,方法调用/消息发送需要显式方法名称和实例或类).

所以你很可能想要

recognizer = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(didSwipe:)];

您也不直接创建UIGestureRecognizer的实例,但如果是具体的子类,则在本例中为UISwipeGestureRecognizer.

在分配识别器之后,将它附加到您想要识别的视图:

[button addGestureRecognizer:recognizer];

然后在didSwipe:方法中,您可以使用手势识别器的属性来确定滑动的大小/距离/其他属性.

你最好下次阅读一些文档.