UITapGestureRecognizer - 让它在触地时工作，而不是触地?

问题描述

我使用点击事件的目的是对时间非常敏感，所以我很好奇是否有可能在用户触摸时激活 UITapGestureRecognizer，而不是要求他们也触摸?

What I'm using the tap event for is very time-sensitive, so I'm curious if it's possible to make UITapGestureRecognizer activate when the user simply touches down, rather than requiring them to touch up as well?

推荐答案

创建您的自定义 TouchDownGestureRecognizer 子类并在 touchesBegan 中实现手势:

Create your custom TouchDownGestureRecognizer subclass and implement gesture in touchesBegan:

TouchDownGestureRecognizer.h

TouchDownGestureRecognizer.h

#import <UIKit/UIKit.h>

@interface TouchDownGestureRecognizer : UIGestureRecognizer

@end

TouchDownGestureRecognizer.m

TouchDownGestureRecognizer.m

#import "TouchDownGestureRecognizer.h"
#import <UIKit/UIGestureRecognizerSubclass.h>

@implementation TouchDownGestureRecognizer
-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event{
    if (self.state == UIGestureRecognizerStatePossible) {
        self.state = UIGestureRecognizerStateRecognized;
    }
}

-(void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event{
    self.state = UIGestureRecognizerStateFailed;
}

-(void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event{
    self.state = UIGestureRecognizerStateFailed;
}


@end

实现:

#import "TouchDownGestureRecognizer.h"
    TouchDownGestureRecognizer *touchDown = [[TouchDownGestureRecognizer alloc] initWithTarget:self action:@selector(handleTouchDown:)];
    [yourView addGestureRecognizer:touchDown];

-(void)handleTouchDown:(TouchDownGestureRecognizer *)touchDown{
    NSLog(@"Down");
}

Swift 实现:

---

Swift implementation:

import UIKit
import UIKit.UIGestureRecognizerSubclass

class TouchDownGestureRecognizer: UIGestureRecognizer
{
    override func touchesBegan(touches: Set<UITouch>, withEvent event: UIEvent)
    {
        if self.state == .Possible
        {
            self.state = .Recognized
        }
    }

    override func touchesMoved(touches: Set<UITouch>, withEvent event: UIEvent)
    {
        self.state = .Failed
    }

    override func touchesEnded(touches: Set<UITouch>, withEvent event: UIEvent)
    {
        self.state = .Failed
    }
}

这是 2017 年要粘贴的 Swift 语法:

---

Here is the Swift syntax for 2017 to paste:

import UIKit.UIGestureRecognizerSubclass

class SingleTouchDownGestureRecognizer: UIGestureRecognizer {
    override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent) {
        if self.state == .possible {
            self.state = .recognized
        }
    }
    override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent) {
        self.state = .failed
    }
    override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent) {
        self.state = .failed
    }
}

请注意，这是 UITap 的替代品.所以在代码中...

Note that this is a drop-in replacement for UITap. So in code like...

func add(tap v:UIView, _ action:Selector) {
    let t = UITapGestureRecognizer(target: self, action: action)
    v.addGestureRecognizer(t)
}

您可以安全地切换到....

you can safely swap to....

func add(hairtriggerTap v:UIView, _ action:Selector) {
    let t = SingleTouchDownGestureRecognizer(target: self, action: action)
    v.addGestureRecognizer(t)
}

测试表明它不会被多次调用.它可以作为替代品；你可以在两个调用之间交换.

Testing shows it will not be called more than once. It works as a drop-in replacement; you can just swap between the two calls.

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