选择文本和更改属性错误？

Question

我在进行简单的文本选择和属性更改时遇到问题。我似乎无法让程序通过第一步。它说selectedRange 为零。为什么会这样？这是一个错误吗？

func selectText() {
    if let textRange = textView?.selectedRange {
        let attributes = [NSAttributedString.Key.font: UIFont(name: "Arial", size: 18.0)]
        textView.textStorage.addAttributes(attributes as [NSAttributedString.Key : Any], range: textRange)
    }
}

使用来自@DionizB 的代码进行编辑（不工作）

我从另一个包含 KeyboardAccessory 视图的 Swift 文件中调用它。该文件中的代码是：

class KeyboardAccessory: UIView {
let VC = ViewController()
@IBAction func boldButtonTapped(_ sender: Any) {
    print("boldButtonTapped -> Sending to bold()")
    VC.bold()
    }
}

现在主 ViewController 中的代码是：

var selectedRange: NSRange?

func textViewDidChangeSelection(_ textView: UITextView) {
    selectedRange = textView.selectedRange
    print(selectedRange)
}

func bold() {
    print("Starting bold()")
    print(selectedRange)
    if let textRange = selectedRange {
        print(textRange)
        let attributes = [NSAttributedString.Key.font: UIFont.systemFont(ofSize: 17, weight: UIFont.Weight.thin)]
        textView.textStorage.addAttributes(attributes as [NSAttributedString.Key : Any], range: textRange)
    }
}

textViewDidChangeSelection 正在打印 selectedRange 但是当从 KeyboardAccessory 视图调用 bold() 时它打印 nil！我如何加载 AccessoryView。

override func viewDidLoad() {
    super.viewDidLoad()
    textView.inputAccessoryView = Bundle.main.loadNibNamed("KeyboardAccessory", owner: self, options: nil)?.first as! UIView?
}

Answer 1

在viewDidLoad() 上确保添加textView.delegate = self。 同样在你的类中继承自UITextViewDelegate。

然后在textViewDidChangeSelection(_:)中拨打您的selectText()

func textViewDidChangeSelection(_ textView: UITextView) {
    selectText()
}

它会正常工作。

编辑 通常，即使您在按钮操作中调用selectText()，它也应该可以工作。但由于它不起作用，让我们做一个解决方法： 在你的课堂上声明var selectedRange: NSRange?。

然后在

func textViewDidChangeSelection(_ textView: UITextView) {
    selectedRange = textView.selectedRange
}

然后在您的selectText() 中执行此操作

func selectText() {
    if let textRange = selectedRange {
        let attributes = [NSAttributedString.Key.font: UIFont(name: "Arial", size: 18.0)]
        textView.textStorage.addAttributes(attributes as [NSAttributedString.Key : Any], range: textRange)
    }
}

为 AccessoryView 编辑

更新您的键盘配件：

class KeyboardAccessory: UIView {
    var boldAction: (() -> Void)? // This is a closure, give it a read after making your button work
    @IBAction func boldButtonTapped(_ sender: Any) {
        print("boldButtonTapped -> Sending to bold()")
        boldAction?()
    }
}

尝试将您加载的笔尖转换为 KeyboardAccessory 并像这样访问您的操作：

override func viewDidLoad() {
    super.viewDidLoad()
    var keyboardAccessory = Bundle.main.loadNibNamed("KeyboardAccessory", owner: self, options: nil)?.first as! KeyboardAccessory?
    keyboardAccessory.boldAction = { [weak self] in // to avoid retain cycles, read also about these
        self?.selectText()
    }
    textView.inputAccessoryView = keyboardAccessory
}