这个平移手势识别器动作有什么问题？

Question

我不确定为什么当我移动视图时这不会平移？

CGPoint translation = [recognizer translationInView:self.view];


    if ((recognizer.view.frameY + translation.y >= self.view.frameHeight - recognizer.view.frameHeight)) {
        CGPoint newOrigin = CGPointMake(self.view.bounds.size.width, roundf(recognizer.view.frameY + translation.y));
        recognizer.view.frameOrigin = newOrigin;
        NSLog(@"FRAME ORIGIN %@", NSStringFromCGPoint(recognizer.view.frameOrigin));
    } 

Answer 1

我不清楚你的一些自定义变量等,所以我没有调试你的代码,我想我会告诉你如何使用a来拖动视图UIPanGestureRecognizer.

因此,假设(a)手势已被添加到被拖动的视图中; (b)该视图包含在您想要约束视图移动的超级视图中,代码可能如下所示:

- (void)handlePan:(UIPanGestureRecognizer *)gesture
{
    static CGRect originalFrame;

    if (gesture.state == UIGestureRecognizerStateBegan)
    {
        originalFrame = gesture.view.frame;
    }
    else if (gesture.state == UIGestureRecognizerStateChanged)
    {
        CGPoint translate = [gesture translationInView:gesture.view.superview];
        CGRect newFrame = CGRectMake(originalFrame.origin.x + translate.x,
                                     originalFrame.origin.y + translate.y,
                                     originalFrame.size.width,
                                     originalFrame.size.height);

        if (CGRectContainsRect(gesture.view.superview.bounds, newFrame))
            gesture.view.frame = newFrame;
    }
}

虽然上述内容非常简单,但我认为我们可以改善用户体验.值得注意的是,如果用户将视图拖到其超视图之外,上面的代码将不会执行任何操作(例如,拖过左边框并在那里冻结,即使您上下移动手指;也不是非常优雅).我认为以下是一个更优雅的用户界面(但读取代码要复杂一点),当用户拖动他们的手指时,我们会将对象拖动到superview中最接近的点,对应于用户的手指是.

- (void)handlePan:(UIPanGestureRecognizer *)gesture
{
    static CGRect originalFrame;

    if (gesture.state == UIGestureRecognizerStateBegan)
    {
        originalFrame = gesture.view.frame;
    }
    else if (gesture.state == UIGestureRecognizerStateChanged)
    {
        CGPoint translate = [gesture translationInView:gesture.view.superview];
        CGRect newFrame = CGRectMake(fmin(gesture.view.superview.frame.size.width - originalFrame.size.width, fmax(originalFrame.origin.x + translate.x, 0.0)),
                                     fmin(gesture.view.superview.frame.size.height - originalFrame.size.height, fmax(originalFrame.origin.y + translate.y, 0.0)),
                                     originalFrame.size.width,
                                     originalFrame.size.height);

        gesture.view.frame = newFrame;
    }
}