iPhone:设置所需的滑动手势长度

Question

我想知道是否有一种简单的方法来设置最小滑动长度，即用户需要滑动的像素长度，以便将手势识别为滑动。

我注意到正常的滑动可能 react 迟钝(例如与滑动照片库中的照片相比)。

这是正常的方式，但我想减少滑动所需的长度:

    - (void)viewDidLoad 
    {


    // SWIPING GESTURES:

    UISwipeGestureRecognizer *swipeLeftRecognizer;
    swipeLeftRecognizer=[[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(foundLeftSwipe:)];
    swipeLeftRecognizer.direction=UISwipeGestureRecognizerDirectionLeft;
    //swipeRecognizer.numberOfTouchesRequired=1;
    [self.view addGestureRecognizer:swipeLeftRecognizer];
    [swipeLeftRecognizer release];

    UISwipeGestureRecognizer *swipeRightRecognizer;
    swipeRightRecognizer=[[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(foundRightSwipe:)];
    swipeRightRecognizer.direction=UISwipeGestureRecognizerDirectionRight;
    //swipeRecognizer.numberOfTouchesRequired=1;
    [self.view addGestureRecognizer:swipeRightRecognizer];
    [swipeRightRecognizer release];


    [super viewDidLoad];
}

#pragma mark -
#pragma mark Swipes

- (void)foundLeftSwipe:(UISwipeGestureRecognizer *)recognizer {
    // do something
}

- (void)foundRightSwipe:(UISwipeGestureRecognizer *)recognizer {
    // do something
    }

我记得有一种方法可以获取像素的起始位置和结束位置，然后将两者进行比较，但我只是想知道是否有更简单的方法，即通过简单地在我这里有代码。

---

编辑:

这就是我重新编码整个事情的方式:

    - (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
    UITouch *touch = [touches anyObject];
    gestureStartPoint = [touch locationInView:self.view];
}

- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
    UITouch *touch = [touches anyObject];
    CGPoint currentPosition = [touch locationInView:self.view];

    CGFloat deltaXX = (gestureStartPoint.x - currentPosition.x); // positive = left, negative = right
    CGFloat deltaYY = (gestureStartPoint.y - currentPosition.y); // positive = up, negative = down

    CGFloat deltaX = fabsf(gestureStartPoint.x - currentPosition.x); // will always be positive
    CGFloat deltaY = fabsf(gestureStartPoint.y - currentPosition.y); // will always be positive

    if (deltaX >= kMinimumGestureLength && deltaY <= kMaximumVariance) {
        if (deltaXX > 0) {
                label.text = @"Horizontal Left swipe detected";
                [self performSelector:@selector(eraseText) withObject:nil afterDelay:2];
            }
        else {
                label.text = @"Horizontal Right swipe detected";
                [self performSelector:@selector(eraseText) withObject:nil afterDelay:2];
            }

    }


    if (deltaY >= kMinimumGestureLength && deltaX <= kMaximumVariance) {
        if (deltaYY > 0) {
            label.text = @"Vertical up swipe detected";
            [self performSelector:@selector(eraseText) withObject:nil afterDelay:2];
            }
        else {
            label.text = @"Vertical down swipe detected";
            [self performSelector:@selector(eraseText) withObject:nil afterDelay:2];
        }


    }



}

Answer 1

我遇到了完全相同的事情，我正在寻找解决方案。 UISwipeGestureRecognizer 中没有required distance 之类的东西，但这并不是您可以使用的全部。我最终使用了 UIPanGestureRecognizer!它看起来像是一个父类(super class)的滑动手势识别器，它肯定会公开更多有用的数据。

这个类中有一个名为 translationInView:(UIView *)aView 的方法，它返回一个 CGPoint，其中 x & y 是整个平移手势的总距离!对我们的要求非常有用的东西!它通过正值和负值来尊重方向，意思是:y=+100 -> 向上向下滑动 100 点，x=+100 滑动从左到右 100 点等等……

我正在做的是检查用户是否已经平移了给定的点数(我正在寻找类似向下滑动的东西，所以对我来说它是 y>150)然后做我的东西...

这里是一些代码摘录:

  -(void)viewDidLoad
    {
    UIPanGestureRecoginzer *panDown=[[UIPanGestureRecoginzer alloc] initWithTarget:self action:@selector(swipedDown:)];
     [self.view addGestureRecognizer:panDown];
    }
    .
    .
    .
    -(void)swipedDown:(UIPanGestureRecoginzer *)recognizer
    {
    CGPoint panned=[recognizer translationInView:self.view];
    if(panned.y>150){
    //swiped down for 150 points
        doSomething();
       }
    }

它还为您提供平移速度:velocityInView:

注意:如果你想有一个整体的平移效果，你应该使用你的父 View (大多数情况下是self.view)。

希望这会有所帮助:UIPanGestureRecognize Class Reference