以编程方式使用 AutoLayout 和 UIScrollView [英] Using AutoLayout and UIScrollView programmatically

问题描述

我正在尝试从这里复制这个问题的答案:Xamarin iOS:滚动视图中的自动布局?但不使用界面构建器.代码很简单，我有 _scrollView 背景色为绿色.然后我有 _contentView 背景颜色为红色.我将 _contentView 添加到 _scrollView 并将 _scrollView 添加到 ViewController 中的 View.当我运行它时，我得到的只是绿色控制器，红色控制器从未出现在里面.

I am trying to make a copy of the answer from this question here: Xamarin iOS: Auto Layout within scroll view? but without using the interface builder. The code is simple, I have _scrollView which has background color green. Then I have _contentView which has background color red. I add _contentView to _scrollView and I add _scrollView to View in the ViewController. When I run this, all I get is Green controller, the red one never appears inside of it.

public async override void ViewDidLoad()
{
    base.ViewDidLoad();

    //ui
    View.BackgroundColor = UIColor.White;

    //views
    _scrollView = new UIScrollView();
    _scrollView.BackgroundColor = UIColor.Green;
    _scrollView.TranslatesAutoresizingMaskIntoConstraints = false;

    _contentView = new UIView();
    _contentView.TranslatesAutoresizingMaskIntoConstraints = false;
    _contentView.BackgroundColor = UIColor.Red;

    var label = new UILabel();
    label.TranslatesAutoresizingMaskIntoConstraints = false;
    label.Text = "Text";

    _contentView.AddSubview(label);

    _scrollView.AddSubview(_contentView);

    View.AddSubviews(new UIView[] { _scrollView });

    _scrollView.TopAnchor.ConstraintEqualTo(View.TopAnchor, 100).Active = true;
    _scrollView.LeftAnchor.ConstraintEqualTo(View.LeftAnchor, 20).Active = true;
    _scrollView.RightAnchor.ConstraintEqualTo(View.RightAnchor, -20).Active = true;
    _scrollView.BottomAnchor.ConstraintEqualTo(View.BottomAnchor, -100).Active = true;

    _contentView.TopAnchor.ConstraintEqualTo(_contentView.Superview.TopAnchor).Active = true;
    _contentView.RightAnchor.ConstraintEqualTo(_contentView.Superview.RightAnchor).Active = true;
    _contentView.LeftAnchor.ConstraintEqualTo(_contentView.Superview.LeftAnchor).Active = true;
    _contentView.BottomAnchor.ConstraintEqualTo(_contentView.Superview.BottomAnchor).Active = true;
    _contentView.WidthAnchor.ConstraintEqualTo(_contentView.Superview.WidthAnchor).Active = true;

    label.TopAnchor.ConstraintEqualTo(label.Superview.TopAnchor, 100).Active = true;
    label.BottomAnchor.ConstraintEqualTo(label.Superview.BottomAnchor, 100).Active = true;
    label.LeftAnchor.ConstraintEqualTo(label.Superview.LeftAnchor, 100).Active = true;
    label.RightAnchor.ConstraintEqualTo(label.Superview.RightAnchor, 100).Active = true;
}

推荐答案

我能够使它工作的唯一方法是将 BottomAnchor 添加到 ContentView 中的最后一个 UIView.我创建了一个带有演示代码的 GitHub 存储库 here

The only way I was able to make it work was by adding BottomAnchor to the last UIView inside ContentView. I created a GitHub repo with demo code here

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