swift - 按下键盘上的返回键时，UITextView 不记得字体样式

Question

我在 Storyboard中有一个 UITextView (文本属性已归属，并选​​中允许编辑属性、选定的、可编辑的)。当用户按下按钮时，我想“激活”粗体字体。因此，无论用户从那里输入什么内容都必须以粗体显示。当按下返回键时，我想转到下一行，并且 UITextView 应该记住所有文本的属性。问题是，按回车键后，所有字符都变为粗体。

这是我的代码。

var isBoldTyping: Bool = false

func textView(_ textView: UITextView, shouldChangeTextIn range: NSRange, replacementText text: String) -> Bool {
    print("text: \(text)", range)
    if text == "\n" {
        textView.text.append("\n")


        if isBoldTyping {
            //textView.typingAttributes = [NSAttributedStringKey.font.rawValue: regularText]
            isBoldTyping = false
        }

    }

    if isBoldTyping {
        textView.textStorage.beginEditing()
        textView.textStorage.addAttributes([NSAttributedStringKey.font: boldText], range: range)
        print("Atttributed adding")
        textView.textStorage.endEditing()
    } else {
        textView.textStorage.beginEditing()
        textView.textStorage.addAttributes([NSAttributedStringKey.font: regularText], range: range)
        print("Atttributed adding")
        textView.textStorage.endEditing()
    }

    return true
}

我想要实现的另一个例子是 stackoverflow 编辑效果。当我按“{}”图标时，我处于“可编码模式”。当按下键盘中的回车键时，它会恢复正常。

regularText和boldText属性只是大小为14的系统字体。

Answer 1

如果我清楚地理解您想要实现的目标，那么您需要的是typingAttributes。当 \n 通过 typingAttributes 出现在 replacementText 中时，您需要禁用粗体。我给你写一个小例子

class ViewController: UIViewController, UITextViewDelegate {

    let textView = UITextView()
    let boldButton = UIButton(type: .system)

    override func viewDidLoad() {
        super.viewDidLoad()

        textView.translatesAutoresizingMaskIntoConstraints = false
        textView.delegate = self
        textView.typingAttributes = [NSAttributedStringKey.font.rawValue: UIFont.systemFont(ofSize: 14.0)]

        view.addSubview(textView)

        view.addConstraint(NSLayoutConstraint(item: view, attribute: .leading, relatedBy: .equal, toItem: textView, attribute: .leading, multiplier: 1.0, constant: 0.0))
        view.addConstraint(NSLayoutConstraint(item: view, attribute: .top, relatedBy: .equal, toItem: textView, attribute: .top, multiplier: 1.0, constant: 0.0))
        view.addConstraint(NSLayoutConstraint(item: view, attribute: .bottom, relatedBy: .equal, toItem: textView, attribute: .bottom, multiplier: 1.0, constant: 0.0))
        view.addConstraint(NSLayoutConstraint(item: view, attribute: .trailing, relatedBy: .equal, toItem: textView, attribute: .trailing, multiplier: 1.0, constant: 0.0))

        boldButton.setTitle("BOLD", for: .normal)
        boldButton.addTarget(self, action: #selector(toggleBold), for: .touchUpInside)
        boldButton.translatesAutoresizingMaskIntoConstraints = false

        view.addSubview(boldButton)
        view.addConstraint(NSLayoutConstraint(item: view, attribute: .leading, relatedBy: .equal, toItem: boldButton, attribute: .leading, multiplier: 1.0, constant: 0.0))
        view.addConstraint(NSLayoutConstraint(item: boldButton, attribute: .height, relatedBy: .equal, toItem: nil, attribute: .notAnAttribute, multiplier: 1.0, constant: 64.0))
        view.addConstraint(NSLayoutConstraint(item: view, attribute: .bottom, relatedBy: .equal, toItem: boldButton, attribute: .bottom, multiplier: 1.0, constant: 0.0))
        view.addConstraint(NSLayoutConstraint(item: view, attribute: .trailing, relatedBy: .equal, toItem: boldButton, attribute: .trailing, multiplier: 1.0, constant: 0.0))

    }

    @objc func toggleBold() {
        boldButton.isSelected = !boldButton.isSelected
        if boldButton.isSelected {
            textView.typingAttributes = [NSAttributedStringKey.font.rawValue: UIFont.boldSystemFont(ofSize: 14.0)]
        } else {
            textView.typingAttributes = [NSAttributedStringKey.font.rawValue: UIFont.systemFont(ofSize: 14.0)]
        }
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }

    func textView(_ textView: UITextView, shouldChangeTextIn range: NSRange, replacementText text: String) -> Bool {
        if text.contains("\n") && boldButton.isSelected {
            toggleBold()
        }
        return true
    }

}