Question

我正在以编程方式创建UIScrollView。当我将所有标签和按钮添加到UIScrollView时，它将不再滚动，如果超出视图，我将看不到任何内容。我是以编程方式创建视图和UIScrollViews的新手。我已经省略了一些代码，例如UILabels，因为它是重复的，而且都与stepTwo UILabel匹配。

  lazy var scrollView: UIScrollView = {
    let view = UIScrollView()
    view.translatesAutoresizingMaskIntoConstraints = false
    view.contentSize.height = 1200
    return view
}()
 let stepTwo: UILabel = {
    let label = UILabel()

    let attributedTitle = NSMutableAttributedString(string: "Step 2:\n", attributes: [NSAttributedString.Key.font: UIFont.systemFont(ofSize: 45)])

    attributedTitle.append(NSAttributedString(string: "See Your Doctor", attributes: [NSAttributedString.Key.font: UIFont.boldSystemFont(ofSize: 20)]))

    label.attributedText = attributedTitle
    label.numberOfLines = 2
    return label
}()
 override func viewDidLoad(){
    super.viewDidLoad()
    view.addSubview(scrollView)
    setupScrollView()
    setupScrollViewLabels()
}
 func setupScrollView(){

     scrollView.anchor(top: view.topAnchor, left: view.leftAnchor, bottom: view.bottomAnchor, right: view.rightAnchor, paddingTop: 200, paddingLeft: 0, paddingBottom: 0, paddingRight: 0, width: 0, height: 0)

}
func setupScrollViewLabels(){
    scrollView.addSubview(stepOne)
    scrollView.addSubview(stepOneDetails)
    scrollView.addSubview(reportButton)
    scrollView.addSubview(stepTwo)
    scrollView.addSubview(stepTwoDetails)

    stepOne.topAnchor.constraint(equalTo: scrollView.topAnchor).isActive = true

    stepOne.leadingAnchor.constraint(equalTo: scrollView.leadingAnchor).isActive = true

    stepOne.trailingAnchor.constraint(equalTo: scrollView.trailingAnchor).isActive = true
    stepOne.bottomAnchor.constraint(equalTo: scrollView.bottomAnchor).isActive = true

    stepOne.widthAnchor.constraint(equalTo: scrollView.widthAnchor).isActive = true


    stepOne.anchor(top: scrollView.topAnchor, left: view.leftAnchor, bottom: scrollView.bottomAnchor, right: view.rightAnchor, paddingTop: 10, paddingLeft: 20, paddingBottom: 0, paddingRight: 20, width: 0, height: 0)

    stepOneDetails.anchor(top: stepOne.bottomAnchor, left: view.leftAnchor, bottom: nil, right: view.rightAnchor, paddingTop: 10, paddingLeft: 20, paddingBottom: 0, paddingRight: 10, width: 0, height: 0)
    reportButton.anchor(top: stepOneDetails.bottomAnchor, left: view.leftAnchor, bottom: nil, right: view.rightAnchor, paddingTop: 30, paddingLeft: 20, paddingBottom: 0, paddingRight: 20, width: 0, height: 50)

    stepTwo.anchor(top: reportButton.bottomAnchor, left: view.leftAnchor, bottom: nil, right: view.rightAnchor, paddingTop: 25, paddingLeft: 20, paddingBottom: 0, paddingRight: 20, width: 0, height: 0)

    stepTwoDetails.anchor(top: stepTwo.bottomAnchor, left: view.leftAnchor, bottom: nil, right: view.rightAnchor, paddingTop: 10, paddingLeft: 20, paddingBottom: 0, paddingRight: 10, width: 0, height: 0)
}

Answer 1

首先，不要设置滚动视图的_when。使用自动布局和约束，让系统为您进行计算。

第二，确保您具有从上到下的完整约束链。您的顶部元素（标签）需要限制在滚动视图的顶部，而您的底部元素（标签）需要限制在滚动视图的底部。所有其他垂直约束应从其上方元素的底部开始。

第三，我强烈建议不使用任何类型的“约束便利”功能/扩展名（例如，您使用的.contentHeight）。至少在您完全了解约束的工作原理之前，请使用以下格式：

.anchor(top: left: bottom: ....)

只有一个小类型，更多的可读性，并且您了解每个约束应该做什么。

第四，在处理布局时，我还建议在视图，标签等上设置背景颜色。这样可以更轻松地查看边框和间距。

所以-这是一个以您发布的代码为基础的示例。我使元素之间的垂直间距大于代码中的间距...在iPhone X上，没有足够的内容滚动。这应该做。如果仍无法在“ X”上滚动，请在iPhone 7（模拟器或设备）上运行它。有很多注释说明了约束设置。

    NSLayoutConstraint.activate([

        // stepOne to top + 10 padding and leading/trailing + 20 padding
        stepOne.topAnchor.constraint(equalTo: scrollView.topAnchor, constant: 10.0),
        stepOne.leadingAnchor.constraint(equalTo: scrollView.leadingAnchor, constant: 20.0),
        stepOne.trailingAnchor.constraint(equalTo: scrollView.trailingAnchor, constant: 20.0),

        // and so on...
    ])

添加UILabel进行查看时，UIScrollView无法正常工作

1 个答案: