ios - firstRect(对于 :) returns wrong value in UITextField

Question

我正在尝试进行语法高亮显示以标记用户输入的错误。

遵循 Get X and Y coordinates of a word in UITextView 中的建议我的代码非常适合 UITextView

但是，我现在正尝试为 UITextField 做类似的事情，但遇到了麻烦。

UITextField 和 UITextView 都符合 UITextInput 并且定位矩形所需的所有方法都应该适用于两者。

这是 UITextView 的函数

func findRect(forTextMatching match:String, in textView:UITextView) -> CGRect? {
    if let text = textView.text,
       let range = text.range(of: match)
    {
        let offset1 = text.distance(from: text.startIndex, to: range.lowerBound)
        let offset2 = text.distance(from: text.startIndex, to: range.upperBound)

        if let pos1 = textView.position(from: textView.beginningOfDocument, offset: offset1),
        let pos2 = textView.position(from: textView.beginningOfDocument, offset: offset2)
        {
            if let textRange = textView.textRange(from: pos1, to: pos2)
            {
                textView.selectedTextRange = textRange
                let rect = textView.firstRect(for: textRange)
                return rect
            }
        }
    }

    return nil
}

在测试应用程序中运行它并突出显示返回矩形，如下所示:

现在尝试用 UITextField 做同样的事情:

func findRect(forTextMatching match:String, in textField:UITextField) -> CGRect? {
    if let text = textField.text,
       let range = text.range(of: match)
    {
        let offset1 = text.distance(from: text.startIndex, to: range.lowerBound)
        let offset2 = text.distance(from: text.startIndex, to: range.upperBound)

        // beginningOfDocument is nil unless textField is first responder
        textField.becomeFirstResponder()
        defer {
            textField.resignFirstResponder()
        }

        if let pos1 = textField.position(from: textField.beginningOfDocument, offset: offset1),
            let pos2 = textField.position(from: textField.beginningOfDocument, offset: offset2)
        {
            if let textRange = textField.textRange(from: pos1, to: pos2)
            {
                textField.selectedTextRange = textRange
                var rect = textField.firstRect(for: textRange)

                return rect
            }
        }
    }

    return nil
}

第一个问题是 UITextField.beginningOfDocument 为 nil，除非该字段是第一响应者。这很容易处理，因此增加了 becomeFirstResonder 和 resignFirstResponder 行。

在测试应用程序中运行它并突出显示返回的矩形，如下所示:

返回的矩形略有偏移。

Answer 1

这似乎是 UITextField 的错误。在调试中检查 View 层次结构时，在 UITextField 下有一个额外的 View ，其类型为 UIFieldEditor，其框架原点 (7,4)。返回的矩形似乎与此 View 相关，而不是 UITextField。

事实证明，您可以将此框架作为 UITextField 的 editRect 进行访问。

UITextField 的修改函数:

func findRect(forTextMatching match:String, in textField:UITextField) -> CGRect? {
    if let text = textField.text,
       let range = text.range(of: match)
    {
        let offset1 = text.distance(from: text.startIndex, to: range.lowerBound)
        let offset2 = text.distance(from: text.startIndex, to: range.upperBound)

        // beginningOfDocument is nil unless textField is first responder
        textField.becomeFirstResponder()
        defer {
            textField.resignFirstResponder()
        }

        if let pos1 = textField.position(from: textField.beginningOfDocument, offset: offset1),
            let pos2 = textField.position(from: textField.beginningOfDocument, offset: offset2)
        {
            if let textRange = textField.textRange(from: pos1, to: pos2)
            {
                var rect = textField.firstRect(for: textRange)

                // firstRect is actually relative to editingRect, not textField
                let top = textField.editingRect(forBounds: textField.bounds).origin.y
                let left = textField.editingRect(forBounds: textField.bounds).origin.x
                rect = CGRect(x: rect.origin.x+left, y: rect.origin.y+top, width: rect.width, height: rect.height)

                return rect
            }
        }
    }

    return nil
}

产生正确的结果: