ios - 索引处的 Swift 方法 insertSubview 效果很好。但是如何重新定位所有 subview 以便为插入的 subview 腾出空间

Question

我以编程方式向特定 View 添加了 4 个 subview (label1、label2、label3、label4)和约束(label2 顶部取决于 label1 底部等)。现在我使用 insertSubiewAtIndex 方法在索引 1(label5) 处插入另一个 subview 。现在如何刷新 UI，因为约束是动态的，意味着 label5 应该占据 label1 位置，label1 应该占据 label2 位置，依此类推。

这是我的代码

override func viewDidLoad() {
    super.viewDidLoad()

    let label1 = UILabel()
    label1.translatesAutoresizingMaskIntoConstraints = false
    label1.text = "label1"
    label1.numberOfLines = 0
    label1.tag = 1

    self.containerView.addSubview(label1)

    NSLayoutConstraint(item: label1, attribute: .top, relatedBy: .equal, toItem: self.containerView, attribute: .top, multiplier: 1.0, constant: 16.0).isActive = true

    NSLayoutConstraint(item: label1, attribute: .leading, relatedBy: .equal, toItem: self.containerView, attribute: .leadingMargin, multiplier: 1.0, constant: 0.0).isActive = true

    NSLayoutConstraint(item: label1, attribute: .trailing, relatedBy: .equal, toItem: self.containerView, attribute: .trailingMargin, multiplier: 1.0, constant: 0.0).isActive = true


    let label2 = UILabel()
    label2.translatesAutoresizingMaskIntoConstraints = false
    label2.text = "label2"
    label2.numberOfLines = 0
    label2.tag = 1

    self.containerView.addSubview(label2)

    NSLayoutConstraint(item: label2, attribute: .top, relatedBy: .equal, toItem: self.containerView.subviews[self.containerView.subviews.count - 2], attribute: .top, multiplier: 1.0, constant: 16.0).isActive = true

    NSLayoutConstraint(item: label2, attribute: .leading, relatedBy: .equal, toItem: self.containerView, attribute: .leadingMargin, multiplier: 1.0, constant: 0.0).isActive = true

    NSLayoutConstraint(item: label2, attribute: .trailing, relatedBy: .equal, toItem: self.containerView, attribute: .trailingMargin, multiplier: 1.0, constant: 0.0).isActive = true


    let label3 = UILabel()
    label3.translatesAutoresizingMaskIntoConstraints = false
    label3.text = "label3"
    label3.numberOfLines = 0
    label3.tag = 1

    self.containerView.addSubview(label3)

    NSLayoutConstraint(item: label3, attribute: .top, relatedBy: .equal, toItem: self.containerView.subviews[self.containerView.subviews.count - 2], attribute: .top, multiplier: 1.0, constant: 16.0).isActive = true

    NSLayoutConstraint(item: label3, attribute: .leading, relatedBy: .equal, toItem: self.containerView, attribute: .leadingMargin, multiplier: 1.0, constant: 0.0).isActive = true

    NSLayoutConstraint(item: label3, attribute: .trailing, relatedBy: .equal, toItem: self.containerView, attribute: .trailingMargin, multiplier: 1.0, constant: 0.0).isActive = true


    let label4 = UILabel()
    label4.translatesAutoresizingMaskIntoConstraints = false
    label4.text = "label4"
    label4.numberOfLines = 0
    label4.tag = 1

    self.containerView.addSubview(label4)

    NSLayoutConstraint(item: label4, attribute: .top, relatedBy: .equal, toItem: self.containerView.subviews[self.containerView.subviews.count - 2], attribute: .top, multiplier: 1.0, constant: 16.0).isActive = true

    NSLayoutConstraint(item: label4, attribute: .leading, relatedBy: .equal, toItem: self.containerView, attribute: .leadingMargin, multiplier: 1.0, constant: 0.0).isActive = true

    NSLayoutConstraint(item: label4, attribute: .trailing, relatedBy: .equal, toItem: self.containerView, attribute: .trailingMargin, multiplier: 1.0, constant: 0.0).isActive = true

    let label5 = UILabel()
    label5.translatesAutoresizingMaskIntoConstraints = false
    label5.text = "label5"
    label5.numberOfLines = 0
    label5.tag = 1

    self.containerView.addSubview(label5)

    NSLayoutConstraint(item: label5, attribute: .top, relatedBy: .equal, toItem: self.containerView.subviews[0], attribute: .top, multiplier: 1.0, constant: 16.0).isActive = true

    NSLayoutConstraint(item: label5, attribute: .leading, relatedBy: .equal, toItem: self.containerView, attribute: .leadingMargin, multiplier: 1.0, constant: 0.0).isActive = true

    NSLayoutConstraint(item: label5, attribute: .trailing, relatedBy: .equal, toItem: self.containerView, attribute: .trailingMargin, multiplier: 1.0, constant: 0.0).isActive = true

}

Answer 1

override func viewDidLoad() {
        super.viewDidLoad()

        containerView.backgroundColor = .white
        let label1 = UILabel()
        label1.translatesAutoresizingMaskIntoConstraints = false
        label1.text = "label1"
        label1.numberOfLines = 0
        label1.tag = 1

        self.containerView.addSubview(label1)

        let label2 = UILabel()
        label2.translatesAutoresizingMaskIntoConstraints = false
        label2.text = "label2"
        label2.numberOfLines = 0
        label2.tag = 1

        self.containerView.addSubview(label2)

        let label3 = UILabel()
        label3.translatesAutoresizingMaskIntoConstraints = false
        label3.text = "label3"
        label3.numberOfLines = 0
        label3.tag = 1

        self.containerView.addSubview(label3)

        let label4 = UILabel()
        label4.translatesAutoresizingMaskIntoConstraints = false
        label4.text = "label4"
        label4.numberOfLines = 0
        label4.tag = 1

        self.containerView.addSubview(label4)

        let label5 = UILabel()
        label5.translatesAutoresizingMaskIntoConstraints = false
        label5.text = "label5"
        label5.numberOfLines = 0
        label5.tag = 1

        self.containerView.addSubview(label5)

        setConstraint(to: [label5, label1, label2, label3, label4])
    }

    private func setConstraint(to views: [UIView]) {
        var iterator  = views.makeIterator()
        var prev: UIView = self.containerView
        while let next = iterator.next() {
            NSLayoutConstraint(item: next, attribute: .top, relatedBy: .equal, toItem: prev, attribute: .top, multiplier: 1, constant: 16).isActive = true
            NSLayoutConstraint(item: next, attribute: .leading, relatedBy: .equal, toItem: self.containerView, attribute: .leadingMargin, multiplier: 1, constant: 0).isActive = true

            NSLayoutConstraint(item: next, attribute: .trailing, relatedBy: .equal, toItem: self.containerView, attribute: .trailingMargin, multiplier: 1, constant: 0).isActive = true
            prev = next
        }
    }