Ios 通过滑动更改自动布局限制

屏幕上有两张图片，它们是通过编程设置的限制。在向左滑动时，图片的大小会发生变化，并变成它们应该的样子。如果在这之后，向右滑动，则什么也不会发生，图片仍保留在原来的位置。 下面是实现代码

func Swipe() {
        let swipeLeft = UISwipeGestureRecognizer(target: self, action: #selector(handleGesture))
        swipeLeft.direction = .left
        self.view.addGestureRecognizer(swipeLeft)

        let swipeRight = UISwipeGestureRecognizer(target: self, action: #selector(handleGesture))
        swipeRight.direction = .right
        self.view.addGestureRecognizer(swipeRight)
    }

    @objc func handleGesture(gesture: UISwipeGestureRecognizer) -> Void {
        if gesture.direction == .right {


            UIView.animate(withDuration: 0.5, delay: 0, usingSpringWithDamping: 1, initialSpringVelocity: 1, options: .curveEaseOut, animations:{

                self.setupLayoutImageOne()
            }, completion: nil)
             self.view.layoutIfNeeded()

        } else if gesture.direction == .left {


            UIView.animate(withDuration: 0.5, delay: 0, usingSpringWithDamping: 1, initialSpringVelocity: 1, options: .curveEaseOut, animations:{
                self.setupLayoutImageTwo()

            }, completion: nil)
            self.view.layoutIfNeeded()
        }
    }


    func setupLayoutImageOne()
    {

       imageOne.translatesAutoresizingMaskIntoConstraints = false
       imageTwo.translatesAutoresizingMaskIntoConstraints = false

        let layoutGuide = view

        NSLayoutConstraint.activate([


            imageOne.topAnchor.constraint(equalTo: layoutGuide!.topAnchor),
            imageOne.leadingAnchor.constraint(equalTo: layoutGuide!.leadingAnchor),
            imageOne.trailingAnchor.constraint(equalTo: layoutGuide!.trailingAnchor,constant: 170) ,
            imageOne.bottomAnchor.constraint(equalTo: layoutGuide!.bottomAnchor,constant: 290),


           imageTwo.bottomAnchor.constraint(equalTo: layoutGuide!.bottomAnchor,constant: 530),
           imageTwo.leadingAnchor.constraint(equalTo: layoutGuide!.leadingAnchor,constant: 200),
           imageTwo.trailingAnchor.constraint(equalTo: layoutGuide!.trailingAnchor,constant: 200),
           imageTwo.topAnchor.constraint(equalTo: layoutGuide!.topAnchor,constant: 800),

            ])

    }
    func setupLayoutImageTwo()
    {

       imageOne.translatesAutoresizingMaskIntoConstraints = false
       imageTwo.translatesAutoresizingMaskIntoConstraints = false

        let layoutGuide = view

        NSLayoutConstraint.activate([


           imageOne.topAnchor.constraint(equalTo: layoutGuide!.topAnchor),
           imageOne.leadingAnchor.constraint(equalTo: layoutGuide!.leadingAnchor),
           imageOne.trailingAnchor.constraint(equalTo: layoutGuide!.trailingAnchor,constant: 299) ,
           imageOne.bottomAnchor.constraint(equalTo: layoutGuide!.bottomAnchor,constant: 570),


           imageTwo.bottomAnchor.constraint(equalTo: layoutGuide!.bottomAnchor),
           imageTwo.leadingAnchor.constraint(equalTo: layoutGuide!.leadingAnchor),
          imageTwo.trailingAnchor.constraint(equalTo: layoutGuide!.trailingAnchor),
           imageTwo.topAnchor.constraint(equalTo: layoutGuide!.topAnchor),
            ])

    }

当我向右滑动时，它会显示这样的错误

将尝试通过打破约束进行恢复 活动，名称：'|'：UIView:0x10080e7a0>

在UIViewAlertForUnsatifiableConstraints处创建符号断点 要在调试器中捕获此信息。研究方法 中列出的UIView上的UIConstraintBasedLayoutDebugging类别 也可能有帮助。致命错误：意外 隐式展开可选值2020-01-28时发现nil 15:09:59.920450+0200 ThemeGame[27748:2857822]致命错误： 隐式展开可选值时意外发现nil

---

由于您已经发布了几个非常类似的问题，我强烈建议您花一些时间学习约束和自动布局是如何工作的

imageView框架看起来相当奇怪，例如这一行：

imageOne.bottomAnchor.constraint(equalTo: layoutGuide!.bottomAnchor,constant: 290)

将imageView的底部290点置于视图底部下方，因此290点像素将脱离屏幕

然而，这里有一种基于您发布的代码的方法。我们为每个imageView的左滑动位置/大小和右滑动位置/大小定义约束。我们将这些约束存储在数组中，然后根据需要激活/停用这些数组：

class SwipeViewController: UIViewController {

    let imageOne: UIImageView = {
        let v = UIImageView()
        v.backgroundColor = .red
        return v
    }()

    let imageTwo: UIImageView = {
        let v = UIImageView()
        v.backgroundColor = .green
        return v
    }()

    // imageOne constraints when swiping Left
    var imageOneLeftConstraints: [NSLayoutConstraint] = [NSLayoutConstraint]()
    // imageOne constraints when swiping Right
    var imageOneRightConstraints: [NSLayoutConstraint] = [NSLayoutConstraint]()
    // imageTwo constraints when swiping Left
    var imageTwoLeftConstraints: [NSLayoutConstraint] = [NSLayoutConstraint]()
    // imageTwo constraints when swiping Right
    var imageTwoRightConstraints: [NSLayoutConstraint] = [NSLayoutConstraint]()

    override func viewDidLoad() {
        super.viewDidLoad()

        imageOne.translatesAutoresizingMaskIntoConstraints = false
        imageTwo.translatesAutoresizingMaskIntoConstraints = false

        view.addSubview(imageOne)
        view.addSubview(imageTwo)

        guard let layoutGuide = view else { fatalError("this should not fail") }

        // local constraint var to reuse
        var c: NSLayoutConstraint


        // define constraints for imageOne when swiping left
        c = imageOne.topAnchor.constraint(equalTo: layoutGuide.topAnchor)
        imageOneLeftConstraints.append(c)
        c = imageOne.leadingAnchor.constraint(equalTo: layoutGuide.leadingAnchor)
        imageOneLeftConstraints.append(c)
        c = imageOne.trailingAnchor.constraint(equalTo: layoutGuide.trailingAnchor,constant: 170)
        imageOneLeftConstraints.append(c)
        c = imageOne.bottomAnchor.constraint(equalTo: layoutGuide.bottomAnchor,constant: 290)
        imageOneLeftConstraints.append(c)

        // define constraints for imageTwo when swiping left
        c = imageTwo.topAnchor.constraint(equalTo: layoutGuide.topAnchor,constant: 800)
        imageTwoLeftConstraints.append(c)
        c = imageTwo.leadingAnchor.constraint(equalTo: layoutGuide.leadingAnchor,constant: 200)
        imageTwoLeftConstraints.append(c)
        c = imageTwo.bottomAnchor.constraint(equalTo: layoutGuide.bottomAnchor,constant: 530)
        imageTwoLeftConstraints.append(c)
        c = imageTwo.trailingAnchor.constraint(equalTo: layoutGuide.trailingAnchor,constant: 200)
        imageTwoLeftConstraints.append(c)


        // define constraints for imageOne when swiping right
        c = imageOne.topAnchor.constraint(equalTo: layoutGuide.topAnchor)
        imageOneRightConstraints.append(c)
        c = imageOne.leadingAnchor.constraint(equalTo: layoutGuide.leadingAnchor)
        imageOneRightConstraints.append(c)
        c = imageOne.trailingAnchor.constraint(equalTo: layoutGuide.trailingAnchor,constant: 299)
        imageOneRightConstraints.append(c)
        c = imageOne.bottomAnchor.constraint(equalTo: layoutGuide.bottomAnchor,constant: 570)
        imageOneRightConstraints.append(c)

        // define constraints for imageTwo when swiping right
        c = imageTwo.topAnchor.constraint(equalTo: layoutGuide.topAnchor)
        imageTwoRightConstraints.append(c)
        c = imageTwo.leadingAnchor.constraint(equalTo: layoutGuide.leadingAnchor)
        imageTwoRightConstraints.append(c)
        c = imageTwo.trailingAnchor.constraint(equalTo: layoutGuide.trailingAnchor)
        imageTwoRightConstraints.append(c)
        c = imageTwo.bottomAnchor.constraint(equalTo: layoutGuide.bottomAnchor)
        imageTwoRightConstraints.append(c)

        // start with imageViews at "swiped left" positions
        NSLayoutConstraint.activate(imageOneLeftConstraints + imageTwoLeftConstraints)

        setupSwipe()
    }

    func setupSwipe() {
        let swipeLeft = UISwipeGestureRecognizer(target: self, action: #selector(handleGesture))
        swipeLeft.direction = .left
        self.view.addGestureRecognizer(swipeLeft)

        let swipeRight = UISwipeGestureRecognizer(target: self, action: #selector(handleGesture))
        swipeRight.direction = .right
        self.view.addGestureRecognizer(swipeRight)
    }

    @objc func handleGesture(gesture: UISwipeGestureRecognizer) -> Void {
        if gesture.direction == .right {

            NSLayoutConstraint.deactivate(imageOneLeftConstraints + imageTwoLeftConstraints)
            NSLayoutConstraint.activate(imageOneRightConstraints + imageTwoRightConstraints)

            UIView.animate(withDuration: 0.5, delay: 0, usingSpringWithDamping: 1, initialSpringVelocity: 1, options: .curveEaseOut, animations:{
                self.view.layoutIfNeeded()
            }, completion: nil)

        } else if gesture.direction == .left {

            NSLayoutConstraint.deactivate(imageOneRightConstraints + imageTwoRightConstraints)
            NSLayoutConstraint.activate(imageOneLeftConstraints + imageTwoLeftConstraints)

            UIView.animate(withDuration: 0.5, delay: 0, usingSpringWithDamping: 1, initialSpringVelocity: 1, options: .curveEaseOut, animations:{
                self.view.layoutIfNeeded()
            }, completion: nil)

        }
    }

}

---

您不能继续添加不同的约束，因为您会遇到冲突。您可以创建一组约束并更改其.constant值，例如，或者您需要在不希望激活的约束上设置.isActive=false，在确实希望激活的约束上设置.isActive=true。顺便说一下。。。我们刚才不是讨论了如何正确地做到这一点吗：？？？是的，你是对的。现在我将重写一些代码，以便您可以禁用属性isActive@DonMag在分配新的限制之前，我尝试重置这些限制。但结果是sameThank你太多了！我会尽可能努力研究这个话题，以免出现类似的情况。