向 UISearchBar 添加动态类型

Question

我的问题在标题中已经说了很多。我正在尝试将动态类型（定义为here）添加到 aUISearchBar没有运气。我知道这是可能的，因为系统应用程序似乎能够很好地处理它，如下所示：

但是，我的应用程序似乎处理得并不好，如下所示：

知道里面UITextField包含UISearchBar我很自然地尝试了这个解决方案，但没有成功： UITextField.appearance(whenContainedInInstancesOf: [UISearchBar.self]).adjustsFontForContentSizeCategory = true

我也尝试过在线搜索/检查文档，但似乎在任何地方都找不到解决方案。我是否缺少让动态类型在UISearchBar.

更新：@matt 建议我手动检查并以这种方式更新字体。但是，这会产生另一个问题，因为搜索栏本身太小而无法容纳文本，如下所示：

@matt 建议也使用该scaledValue(for:)方法更新高度，但这似乎不起作用。这是我正在使用的代码：

override func traitCollectionDidChange(_ previousTraitCollection: UITraitCollection?) {
        super.traitCollectionDidChange(previousTraitCollection)
        UITextField.appearance(whenContainedInInstancesOf: [UISearchBar.self]).font = UIFont.preferredFont(forTextStyle: .body)
        let textFieldFrame = UITextField.appearance(whenContainedInInstancesOf: [UISearchBar.self]).frame
        UITextField.appearance(whenContainedInInstancesOf: [UISearchBar.self]).frame = CGRect(x: textFieldFrame.minX, y: textFieldFrame.minY, width: textFieldFrame.width, height: UIFontMetrics.default.scaledValue(for: textFieldFrame.height))
}

字体现在似乎在用这个更新的代码缩放，但搜索栏的高度没有增长：

override func traitCollectionDidChange(_ previousTraitCollection: UITraitCollection?) {
    super.traitCollectionDidChange(previousTraitCollection)
    searchBar.textField?.font = UIFont.preferredFont(forTextStyle: .body)
    if let textFieldFrame = searchBar.textField?.frame {
        searchBar.textField?.frame = CGRect(x: textFieldFrame.minX, y: textFieldFrame.minY, width: textFieldFrame.width, height: UIFontMetrics.default.scaledValue(for: textFieldFrame.height))
    }
}

另外，这是我找到 textField 的方法（以防其他卡住的用户想知道）：

extension UISearchBar {
    var textField: UITextField? {
        var _textField: UITextField? = nil
        subviews.forEach {
            $0.subviews.forEach {
                if let textField = $0 as? UITextField {
                    _textField = textField
                }
            }
        }
        return _textField
    }
}

Answer 1

我遵循以下里程碑来实现您的目标：

• 使用动态类型功能自动调整字体（第 1 步）。

• 当出现新的首选内容大小类别时，调整搜索栏约束（步骤 2） 及其文本字段约束（步骤 3）。

  class SearchBarDynamicTypeVC: UIViewController {
  
  @IBOutlet weak var mySearchBar: UISearchBar!
  
  let fontHead = UIFont(name: "Chalkduster", size: 20.0)
  let fontHeadMetrics = UIFontMetrics(forTextStyle: .title1)
  var initialFrameHeight: CGFloat = 0.0
  
  
  override func viewDidLoad() {
      super.viewDidLoad()
  
      UITextField.appearance(whenContainedInInstancesOf: [UISearchBar.self]).font = fontHeadMetrics.scaledFont(for: fontHead!)
  
      mySearchBar.textField?.adjustsFontForContentSizeCategory = true //STEP 1
  }
  
  
  override func viewDidAppear(_ animated: Bool) {
      super.viewDidAppear(animated)
  
      initialFrameHeight = mySearchBar.intrinsicContentSize.height
  
      if let textField = mySearchBar.textField {
          adaptConstraints(textField) //Initialization according to the first preferred content size category
      }
  }
  
  
  override func traitCollectionDidChange(_ previousTraitCollection: UITraitCollection?) {
      super.traitCollectionDidChange(previousTraitCollection)
  
      if let textField = mySearchBar.textField,
          let _ = previousTraitCollection {
  
          adaptConstraints(textField) // STEP 2 & 3
      }
  }
  
  
  private func adaptConstraints(_ textField: UITextField) {
  
  //  Adapt the SEARCHBAR constraints
      mySearchBar.translatesAutoresizingMaskIntoConstraints = false
      NSLayoutConstraint.deactivate(mySearchBar.constraints)
  
      let heightSB = mySearchBar.heightAnchor.constraint(equalToConstant: fontHeadMetrics.scaledValue(for: initialFrameHeight))
      let widthSB = mySearchBar.widthAnchor.constraint(equalToConstant: UIScreen.main.bounds.width - 20)
      let centerVSB = mySearchBar.centerYAnchor.constraint(equalTo: self.view.centerYAnchor)
      let centerHSB = mySearchBar.centerXAnchor.constraint(equalTo: self.view.centerXAnchor)
  
      NSLayoutConstraint.activate([centerVSB,
                                   centerHSB,
                                   widthSB,
                                   heightSB])
  
  //  Adapt the SEARCHBAR TEXTFIELD constraints
      textField.translatesAutoresizingMaskIntoConstraints = false
      NSLayoutConstraint.deactivate(textField.constraints)
  
      let centerXTF = textField.centerXAnchor.constraint(equalTo: textField.superview!.centerXAnchor)
      let centerYTF = textField.centerYAnchor.constraint(equalTo: textField.superview!.centerYAnchor)
      let widthTF = textField.widthAnchor.constraint(equalTo: textField.superview!.widthAnchor, constant: -20.0)
      let heightTF = textField.heightAnchor.constraint(equalTo: textField.superview!.heightAnchor, constant: -20.0)
  
      NSLayoutConstraint.activate([centerXTF,
                                   centerYTF,
                                   widthTF,
                                   heightTF])
  }
  }
  

我使用您的帖子中提供的代码片段来获取搜索栏文本字段：

extension UISearchBar {

    var textField: UITextField? {

        var _textField: UITextField? = nil

        subviews.forEach {
            $0.subviews.forEach {
                if let textField = $0 as? UITextField {
                    _textField = textField
                }
            }
        }
        return _textField
    }
}

但是，您也可以使用密钥获取它，searchField如下所示：

let textField = searchBar.value(forKey: "searchField") as? UITextField

下面的快照显示了最终结果：

现在，您可以通过调整上面的代码片段并自定义视觉个人选择（文本样式、字体、边距...）来向 UISearchBar 添加动态类型。