Ios firstRect（for:）在UITextField中返回错误的值

我正在尝试使用语法高亮显示来标记用户输入中的错误

遵循代码中的建议对于UITextView非常有效

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
}

然而，我现在正试图为UITextField做类似的事情，但遇到了麻烦

UITextField和UITextView都符合UITEPUT，定位rect所需的所有方法都应适用于这两种方法

这是UITextView的一个函数

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此命令，并突出显示返回矩形，如下所示：

现在尝试对UITextField执行相同的操作：

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
}

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
}

第一个问题是UITextField.beginingofdocument为零，除非该字段是第一响应者。这很容易处理，因此有额外的线路成为第一响应者和第一响应者

在测试应用程序中运行此命令，并突出显示返回的rect，如下所示：

---

返回的rect略微偏移。

这似乎是UITextField的错误。在调试中检查视图层次结构时，UIFieldEditor类型的UIExtField下有一个额外的视图，具有帧原点（7,4）。返回的rect似乎与此视图相关，而不是UITextField

事实证明，您可以作为UITextField的editRect访问此帧

修改了UITextField的func：

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
}

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
}

生成正确的结果：

务必提交雷达文件。¯_(ツ)_/¯