swift - 从 UIStackView 中移除 UIView 会改变它的大小

Question

我正在尝试构建拖放操作，如果我将 View 从堆栈 View 拖放到某个位置并使用“removeArrangedSubview”删除 View ，它会更改拖动项目的大小并使其变大。我正在使用这段代码来调整掉落元素的大小。

sender.view!.frame = CGRectMake(sender.view!.frame.origin.x, sender.view!.frame.origin.y, sender.view!.frame.width * 0.5, sender.view!.frame.height * 0.5)

这是用于比较的图像。

Answer 1

您正在设置要移动的 View 的框架，但是当您将它放在堆栈 View 中时，堆栈 View 将根据堆栈 View 的约束和您要添加到其中的 View 的固有内容大小重置它。当您不调用 removeArrangedSubview 时它不这样做的原因是因为它没有触发自动布局传递。通常，当您使用自动布局时，您不应设置 View 框架，而应更新约束 intrinsicContentSize 并请求自动布局更新。

您应该尝试使用堆栈 View 的 distribution 属性、对其施加的约束以及要添加到的 View 的 intrinsicContentSize直到你得到你想要的结果。

例如:

class ViewController: UIViewController
{
    let stackView = UIStackView()
    let otherStackView = UIStackView()
    
    override func viewDidLoad()
    {
        self.view.backgroundColor = UIColor.whiteColor()
        
        stackView.alignment = .Center
        stackView.axis = .Horizontal
        stackView.spacing = 10.0
        stackView.distribution = .FillEqually
        stackView.translatesAutoresizingMaskIntoConstraints = false
        
        otherStackView.alignment = .Center
        otherStackView.axis = .Horizontal
        otherStackView.spacing = 10.0
        otherStackView.distribution = .FillEqually
        otherStackView.translatesAutoresizingMaskIntoConstraints = false
        
        self.view.addSubview(stackView)
        self.view.addSubview(otherStackView)
        
        stackView.bottomAnchor.constraintEqualToAnchor(self.view.bottomAnchor).active = true
        stackView.leadingAnchor.constraintEqualToAnchor(self.view.leadingAnchor).active = true
        stackView.trailingAnchor.constraintEqualToAnchor(self.view.trailingAnchor).active = true
        stackView.heightAnchor.constraintEqualToConstant(150).active = true
        
        otherStackView.topAnchor.constraintEqualToAnchor(self.view.topAnchor).active = true
        otherStackView.widthAnchor.constraintGreaterThanOrEqualToConstant(50).active = true
        otherStackView.centerXAnchor.constraintEqualToAnchor(self.view.centerXAnchor).active = true
        otherStackView.heightAnchor.constraintEqualToConstant(150).active = true
        
        self.addSubviews()
    }
    
    func addSubviews()
    {
        for _ in 0 ..< 5
        {
            let view = View(frame: CGRect(x: 0.0, y: 0.0, width: 100, height: 100))
            view.userInteractionEnabled = true
            let panGesture = UIPanGestureRecognizer(target: self, action: #selector(self.panHandler(_:)))
            view.addGestureRecognizer(panGesture)
            view.translatesAutoresizingMaskIntoConstraints = false
            view.backgroundColor = UIColor.redColor()
            self.stackView.addArrangedSubview(view)
        }
    }
    
    func panHandler(sender: UIPanGestureRecognizer)
    {
        guard let view = sender.view else{ return }
        switch sender.state {
        case .Began:
            self.stackView.removeArrangedSubview(view)
            self.view.addSubview(view)
            let location = sender.locationInView(self.view)
            view.center = location
        case .Changed:
            view.center.x += sender.translationInView(self.view).x
            view.center.y += sender.translationInView(self.view).y
        case .Ended:
            if CGRectContainsPoint(self.otherStackView.frame, view.center)
            {
                self.otherStackView.addArrangedSubview(view)
                self.otherStackView.layoutIfNeeded()
            }
            else
            {
                self.stackView.addArrangedSubview(view)
                self.otherStackView.layoutIfNeeded()
            }
        default:
            self.stackView.addArrangedSubview(view)
            self.otherStackView.layoutIfNeeded()
        }
        sender.setTranslation(CGPointZero, inView: self.view)
    }
}

class View: UIView
{
    override func intrinsicContentSize() -> CGSize
    {
        return CGSize(width: 100, height: 100)
    }
}

上面的 View Controller 和 UIView 子类做的事情与您正在寻找的类似，但无法从您的问题中分辨出来。请注意，将堆栈 View 固定到其 super View (如 stackView)的边缘会导致它拉伸(stretch) subview 以填充所有可用空间，同时允许堆栈 View 根据其固有大小动态调整大小 subview (如 otherStackView)没有。

更新

如果您不想将 View 添加到另一个堆栈 View ，但希望它们保留它们的框架，您应该删除 View 对它们的任何约束，然后将它们的 translatesAutoresizingMaskIntoConstraints 属性设置为真。例如:

func panHandler(sender: UIPanGestureRecognizer)
{
    guard let view = sender.view else{ return }
    switch sender.state {
    case .Began:
        self.stackView.removeArrangedSubview(view)
        self.view.addSubview(view)
        let location = sender.locationInView(self.view)
        view.center = location
    case .Changed:
        view.center.x += sender.translationInView(self.view).x
        view.center.y += sender.translationInView(self.view).y
    default:
        view.removeConstraints(view.constraints)
        view.translatesAutoresizingMaskIntoConstraints = true
        // You can now set the view's frame or position however you want
        view.center.x += sender.translationInView(self.view).x
        view.center.y += sender.translationInView(self.view).y

    }
    sender.setTranslation(CGPointZero, inView: self.view)
}