改变UIView的高度以响应手指拖动 [英] Changing height of UIView in reponse to finger drag

问题描述

我知道标题有点令人困惑所以我会尽力解释它。我有一个固定宽度为100的UIView，以及从0开始的可变高度。我想要做的是将手指从UIView的底部拖到屏幕的顶部，以及UIView改变它的高度/延伸到我的手指的位置。如果那仍然复杂只是想象它是从一些东西下拉出来的纸条。

I understand that the title is a bit confusing so I'll try my best to explain it well. I have a UIView that has a fixed width of 100, and a variable height that starts at 0. What I want to be able to do is drag my finger from the base of the UIView, towards the top of the screen, and the UIView changes its height/extends to the position of my finger. If that's still to complicated just imagine it as a strip of paper being pulled out from under something.

如果你能提供帮助，那将是非常好的。我认为它不应该太难，但我只是一个初学者，我能理解，如果我没有解释得好！

If you can help, that would be really great. I don't think it should be too hard, but I'm only a beginner and I can understand if I haven't explained it well!

推荐答案

这应该是直接的 UIPanGestureRecognizer 和一点点数学。要将视图更改为正确的框架（我使用名称 _viewToChange ，请稍后将其替换为您的视图），只需添加：

This should be straight-forward with a UIPanGestureRecognizer and a little math. To change the view to the correct frame (I'm using the name _viewToChange, so replace that with your view later), simply add:

UIPanGestureRecognizer * pan = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(pan:)];
pan.maximumNumberOfTouches = pan.minimumNumberOfTouches = 1;
[self addGestureRecognizer:pan];

到超级视图的 init 方法，并定义方法：

to your init method for the super view, and define the method:

- (void)pan:(UIPanGestureRecognizer *)aPan; {
  CGPoint currentPoint = [aPan locationInView:self];

  [UIView animateWithDuration:0.01f
                   animations:^{
                     CGRect oldFrame = _viewToChange.frame;
                     _viewToChange.frame = CGRectMake(oldFrame.origin.x, currentPoint.y, oldFrame.size.width, ([UIScreen mainScreen].bounds.size.height - currentPoint.y));
                   }];
}

这应该会在用户手指移动时为视图设置动画。希望有帮助！

This should animate the view up as the users finger moves. Hope that Helps!

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