iPhone:使用touchesBegan、touchesMoved和touchesEnded平移移动图像

Question

我的 View 中有一个图像，其中包含 9x9 网格。我想使用平移移动沿网格移动对象，该网格由另一个数组(9)内的列数组(9)组成。图像应在网格中从一个正方形移动到另一个正方形。下面的代码是我到目前为止所拥有的。问题是图像一次跳动 3 - 4 个方格。它太敏感了。任何人都可以阐明原因并就如何解决此敏感问题提出一些建议吗？

有效的代码:

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

    // Do not move if touch is off the grid
    if (gestureStartPoint.x < 0 || 
        gestureStartPoint.x > 450 || 
        gestureStartPoint.y < 0 || 
        gestureStartPoint.y > 450) {
        canMove = NO;
    }else {
        canMove = YES;
    }
}

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

    double thresholdX = 50;

    if (canMove) { 
        deltaX = (int)(currentPosition.x - gestureStartPoint.x); 
        if (deltaX > thresholdX) {
            deltaX = 0; 
            if([self blockCanMoveXDir:1]){
                [cBlock movX:1];
            }
            // Resets start point 
            gestureStartPoint = currentPosition; 
            NSLog(@"-------------> Block Moved"); 
        } else if(deltaX < 0 && fabs(deltaX) > thresholdX) {
            deltaX = 0; 
            if([self blockCanMoveXDir:-1]){
                [cBlock movX:-1];
            }
            gestureStartPoint = currentPosition; 
        }
    }
}

- (void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event {
    canMove = NO;
}

- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event{
    canMove = NO;
}

Answer 1

我认为在 if (canMove) { 下面，您应该累积移动量。让我解释一下，您应该以这种方式计算运动的绝对 deltaX:

deltaX = currentPosition.x - gestureStartPoint.x;

其中 deltaX 是一个类变量。当该值大于阈值时，您将进行一格移动。调整该阈值可以改变灵敏度。当然，您还必须考虑 Y 分量。