UITouch触及手指方向和速度 [英] UITouch touchesMoved Finger Direction and Speed

问题描述

如何在touchmoved功能中获得手指移动的速度和方向？

How can I get Speed and Direction of finger movements in touchmoved function?

我想获得手指速度和手指方向并将其应用于UIView类方向移动和动画速度。

I want to get the finger speed and finger direction and apply it in a UIView class direction movement and animation speed.

我读了这个链接，但我无法理解答案，此外它没有解释我如何检测方向：

I read this link but I can not understand the answer, in addition it is not explaining how I can detect the direction:

UITouch移动速度检测

到目前为止，我尝试了这段代码：

so far, I tried this code:

-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
    UITouch *anyTouch = [touches anyObject];
    CGPoint touchLocation = [anyTouch locationInView:self.view];
    //NSLog(@"touch %f", touchLocation.x);
    player.center = touchLocation;
    [player setNeedsDisplay];
    self.previousTimestamp = event.timestamp;    
}

- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
    UITouch *touch = [touches anyObject];
    CGPoint location = [touch locationInView:self.view];
    CGPoint prevLocation = [touch previousLocationInView:self.view];
    CGFloat distanceFromPrevious = [self distanceBetweenPoints:location :prevLocation];
    NSTimeInterval timeSincePrevious = event.timestamp - previousTimestamp;

    NSLog(@"diff time %f", timeSincePrevious);
}

推荐答案

方向将由touchesMoved中location和prevLocation的值。具体而言，位置将包含新的触摸点。例如：

Direction will be determined from the values of "location" and "prevLocation" in touchesMoved. Specifically, location will contain the new point of the touch. For example:

if (location.x - prevLocation.x > 0) {
    //finger touch went right
} else {
    //finger touch went left
}
if (location.y - prevLocation.y > 0) {
    //finger touch went upwards
} else {
    //finger touch went downwards
}

现在，对于给定的手指移动，touchesMoved将被多次调用。当你的手指第一次触摸屏幕时，你的代码比较一个初始值是关键，当运动最终完成时，它与CGPoint的值相比。

Now touchesMoved will get called many times for a given finger movement. It will be key to your code to compare an initial value when the finger first touches the screen, with a value of the CGPoint when the movement is finally complete.

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