滚动视图上不显示文本视图答案

【问题标题】：Text View is not displayed on the scroll view滚动视图上不显示文本视图
【发布时间】：2019-02-08 18:32:11
【问题描述】：

我有一个视图控制器名称为 TeamDetailsViewController。我以编程方式将滚动视图添加到视图控制器，并将 UITextview 添加为滚动视图的子视图。但是由于未知原因没有显示文本视图。请帮忙。这是我的代码

class TeamDetailsController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()

        navigationController?.navigationBar.prefersLargeTitles = false

        setupViews()
    }

    lazy var scrollView: UIScrollView = {
        let sv = UIScrollView(frame: self.view.bounds)
        sv.backgroundColor = .blue

        sv.autoresizingMask = UIViewAutoresizing(rawValue: UIViewAutoresizing.RawValue(UInt8(UIViewAutoresizing.flexibleWidth.rawValue) | UInt8(UIViewAutoresizing.flexibleHeight.rawValue)))

        sv.contentSize = CGSize(width: self.view.bounds.size.width, height: self.view.bounds.size.height * 2);
        return sv
    }()

    var textView: UITextView = {
        var tv = UITextView()
        tv.textColor = .darkGray
        tv.backgroundColor = .black
        tv.font = UIFont.systemFont(ofSize: 16)
        return tv
    }()

    func setupViews() {

        view.backgroundColor = .white
        view.addSubview(scrollView)            
        scrollView.addSubview(textView)

        scrollView.addConstraintsWithFormat(format: "H:|-16-[v0]-16-|", views: textView)
        scrollView.addConstraintsWithFormat(format: "V:|-16-[v0]-16-|", views: textView)           
    }
}

【问题讨论】：

标签： ios swift uiscrollview uitextview

【解决方案1】：

您在此变体中将 scrollView contentSize 显式设置为框架，您不应将自动布局约束与 scrollView 的子视图一起使用。试试这个：

func setupViews() {
    view.backgroundColor = .white
    view.addSubview(scrollView)
    scrollView.addSubview(textView)
    textView.frame = CGRect.init(origin: CGPoint(0, 0), size: scrollView.contentSize).insetBy(dx: 16, dy: 16)
}

另一个变体是不将scrollView contentSize 显式设置为框架，并将scrollView subViews 约束设置为scrollView 的边缘，并使用约束设置此subViews 的高度和宽度，scrollView 将从该宽度和高度约束中获取内容大小。示例：

view.addSubview(scrollView)
    scrollView.topAnchor.constraint(equalTo: view.topAnchor, constant: 0).isActive = true
    scrollView.leftAnchor.constraint(equalTo: view.leftAnchor, constant: 0).isActive = true
    scrollView.bottomAnchor.constraint(equalTo: view.bottomAnchor, constant: 0).isActive = true
    scrollView.rightAnchor.constraint(equalTo: view.rightAnchor, constant: 0).isActive = true

    scrollView.addSubview(imageView)
    imageView.topAnchor.constraint(equalTo: scrollView.topAnchor, constant: 0).isActive = true
    imageView.leftAnchor.constraint(equalTo: scrollView.leftAnchor, constant: 0).isActive = true
    imageView.bottomAnchor.constraint(equalTo: scrollView.bottomAnchor, constant: 0).isActive = true
    imageView.rightAnchor.constraint(equalTo: scrollView.rightAnchor, constant: 0).isActive = true
imageView.widthAnchor.constraint(equalToConstant: UIScreen.main.bounds.width).isActive = true
imageView.heightAnchor.constraint(equalToConstant: view.frame.height - 32).isActive = true

不要忘记设置滚动视图及其子视图

scrollView.translatesAutoresizingMaskIntoConstraints = false
imageView.translatesAutoresizingMaskIntoConstraints = false

【讨论】：

【解决方案2】：

试试这个代码；

    var textView: UITextView = {
    var tv = UITextView()
    tv.textColor = .darkGray
    tv.backgroundColor = .black
tv.translatesAutoresizingMaskIntoConstraints = false
    tv.font = UIFont.systemFont(ofSize: 16)
    return tv
}()

【讨论】：