ios - 等待 addSubview 成功后再添加另一个 Subview

Question

我正在尝试使用自动布局向我的 ViewController 添加多个 subview 。因此，许多这些 View 都依赖于 anchor 或其他。

我的类(class)在下面

class historyView: UIViewController {

    var resFrame : UIImageView = {
        let image = UIImage(named: "historyFrame.png")
        let imageView = UIImageView(image: image)
        imageView.translatesAutoresizingMaskIntoConstraints = false
        return imageView
    }()

   var timeTitleView : UITextView = {
        let textView = UITextView()
        let titleTxt = NSLocalizedString("Time", comment: "")
        textView.text = titleTxt
        textView.font = UIFont(name: "BPG Nino Mtavruli", size: 20)
        textView.adjustsFontForContentSizeCategory = true
        textView.translatesAutoresizingMaskIntoConstraints = false
        return textView
    }()

    var timeResView : UITextView = {
        let textView = UITextView()
        textView.font = UIFont(name: "BPG Nino Mtavruli", size: 20)
        textView.adjustsFontForContentSizeCategory = true
        textView.translatesAutoresizingMaskIntoConstraints = false
        return textView
    }()

    var dateTitleView : UITextView = {
        let textView = UITextView()
        let titleTxt = NSLocalizedString("Date", comment: "")
        textView.text = titleTxt
        textView.font = UIFont(name: "BPG Nino Mtavruli", size: 20)
        textView.adjustsFontForContentSizeCategory = true
        textView.translatesAutoresizingMaskIntoConstraints = false
        return textView
    }()

    var dateResView : UITextView = {
        let textView = UITextView()
        let comResClass = complileResults()
        let resTxt = comResClass.getResult(key: "date")
        textView.text = resTxt
        textView.font = UIFont(name: "BPG Nino Mtavruli", size: 20)
        textView.adjustsFontForContentSizeCategory = true
        textView.translatesAutoresizingMaskIntoConstraints = false
        return textView
    }()

override func viewDidAppear(_ animated: Bool) {
        showResults()
}

 func showResults() {
    showResFrame() 
    showTime()
    showDate()
}

func showResFrame() {
        view.addSubview(resFrame)
        resFrame.centerXAnchor.constraint(equalTo: self.view.centerXAnchor).isActive = true
        resFrame.centerYAnchor.constraint(equalTo: self.view.centerYAnchor).isActive = true
        resFrame.widthAnchor.constraint(equalToConstant: 350).isActive = true
        resFrame.heightAnchor.constraint(equalToConstant: 500).isActive = true
        showTime()
    }

    func showTime() {
        showTimeTitle()
        showTimeResult()
    }

    func showTimeTitle() {
        let titleTxt = NSLocalizedString("Time", comment: "")
        timeTitleView.text = titleTxt
        timeTitleView.font = UIFont(name: "BPG Nino Mtavruli", size: 20)
        timeTitleView.translatesAutoresizingMaskIntoConstraints = false
        view.addSubview(timeTitleView)
        timeTitleView.topAnchor.constraint(equalTo: resFrame.topAnchor, constant: 15).isActive = true
        timeTitleView.leftAnchor.constraint(equalTo: resFrame.leftAnchor, constant: 175).isActive = true
        timeTitleView.widthAnchor.constraint(equalToConstant: 80).isActive = true
        timeTitleView.heightAnchor.constraint(equalToConstant: 30).isActive = true

    }

    func showTimeResult() {
        let comResClass = complileResults()
        let resTxt = comResClass.getResult(key: "time")
        timeResView.text = resTxt
        view.addSubview(timeResView)
        timeResView.topAnchor.constraint(equalTo: resFrame.topAnchor, constant: 15).isActive = true
        timeResView.leftAnchor.constraint(equalTo: resFrame.leftAnchor, constant: 255).isActive = true
        timeResView.widthAnchor.constraint(equalToConstant: 80).isActive = true
        timeResView.heightAnchor.constraint(equalToConstant: 30).isActive = true
    }

    func showDate() {
        showDateTitle()
        showDateResult()
    }

    func showDateTitle() {
        view.addSubview(dateTitleView)
        dateTitleView.topAnchor.constraint(equalTo: resFrame.topAnchor, constant: 15).isActive = true
        dateTitleView.leftAnchor.constraint(equalTo: resFrame.leftAnchor, constant: 15).isActive = true
        dateTitleView.widthAnchor.constraint(equalToConstant: 80).isActive = true
        dateTitleView.heightAnchor.constraint(equalToConstant: 30).isActive = true
    }

    func showDateResult() {
        let comResClass = complileResults()
        let resTxt = comResClass.getResult(key: "date")
        dateResView.text = resTxt
        view.addSubview(dateResView)
        dateResView.topAnchor.constraint(equalTo: resFrame.topAnchor, constant: 15).isActive = true
        dateResView.leftAnchor.constraint(equalTo: resFrame.leftAnchor, constant: 95).isActive = true
        dateResView.widthAnchor.constraint(equalToConstant: 80).isActive = true
        dateResView.heightAnchor.constraint(equalToConstant: 30).isActive = true
    }

}

当 View 第一次出现时，resFrame UIImageView 出现，但没有其他内容。即使您可以看到它意味着添加 subview 。

如果我返回导航然后再次返回，所有 View 都是正确的!

我在 addSubview(dateTitleView) 行上放置了一个 block 点，并且在看到 resFrame 图像出现之前代码就到达了该行。

所以，我怀疑这些 View 没有出现，因为它们试图锚定尚不存在的东西。

我原以为函数会按顺序处理。我的意思是在 showResFrame() 完成之前不会调用 showTime() 。这不是正在发生的事情吗？

func showResults() {
        showResFrame() 
        showTime()
        showDate()
    }

Answer 1

您需要先将它们添加到 viewDidLoad/viewWillAppear 中，而不是 viewDidAppear

override func viewWillAppear() {
    super.viewWillAppear()
    showResults()
}

viewDidAppear 在 vc 的 View 出现时被调用，所以你会注意到添加