在 Swift 中获取和设置 UITextField 和 UITextView 的光标位置 [英] Getting and Setting Cursor Position of UITextField and UITextView in Swift

问题描述

我一直在试验 UITextField 以及如何处理它的光标位置.我发现了许多关系 Objective-C 答案，如

I've been experimenting with UITextField and how to work with it's cursor position. I've found a number of relation Objective-C answers, as in

• 获取UITextField在ios中的光标位置
• 控制 UITextField 中的光标位置
• UITextField 获取当前编辑的单词

但由于我使用 Swift，我想学习如何获取当前光标位置并在 Swift 中设置它.

But since I am working with Swift, I wanted to learn how to get the current cursor location and also set it in Swift.

下面的答案是我从Objective-C实验和翻译的结果.

The answer below is the the result of my experimentation and translation from Objective-C.

推荐答案

以下内容同时适用于UITextField和UITextView.

The following content applies to both UITextField and UITextView.

文本字段文本的最开始:

The very beginning of the text field text:

let startPosition: UITextPosition = textField.beginningOfDocument

文本字段文本的最后:

let endPosition: UITextPosition = textField.endOfDocument

当前选择的范围:

let selectedRange: UITextRange? = textField.selectedTextRange

获取光标位置

if let selectedRange = textField.selectedTextRange {

    let cursorPosition = textField.offset(from: textField.beginningOfDocument, to: selectedRange.start)

    print("(cursorPosition)")
}

设置光标位置

为了设置位置，所有这些方法实际上都是设置一个具有相同开始和结束值的范围.

Set cursor position

In order to set the position, all of these methods are actually setting a range with the same start and end values.

开始

let newPosition = textField.beginningOfDocument
textField.selectedTextRange = textField.textRange(from: newPosition, to: newPosition)

到最后

let newPosition = textField.endOfDocument
textField.selectedTextRange = textField.textRange(from: newPosition, to: newPosition)

到当前光标位置左侧一个位置

// only if there is a currently selected range
if let selectedRange = textField.selectedTextRange {

    // and only if the new position is valid
    if let newPosition = textField.position(from: selectedRange.start, offset: -1) {

        // set the new position
        textField.selectedTextRange = textField.textRange(from: newPosition, to: newPosition)
    }
}

到任意位置

从头开始向右移动 5 个字符.

Start at the beginning and move 5 characters to the right.

let arbitraryValue: Int = 5
if let newPosition = textField.position(from: textField.beginningOfDocument, offset: arbitraryValue) {

    textField.selectedTextRange = textField.textRange(from: newPosition, to: newPosition)
}

相关

选择所有文本

textField.selectedTextRange = textField.textRange(from: textField.beginningOfDocument, to: textField.endOfDocument)

选择文本范围

// Range: 3 to 7
let startPosition = textField.position(from: textField.beginningOfDocument, offset: 3)
let endPosition = textField.position(from: textField.beginningOfDocument, offset: 7)

if startPosition != nil && endPosition != nil {
    textField.selectedTextRange = textField.textRange(from: startPosition!, to: endPosition!)
}

在当前光标位置插入文本

textField.insertText("Hello")

注意事项

• 使用 textField.becomeFirstResponder() 将焦点放在文本字段上并使键盘出现.

  Notes

  • Use textField.becomeFirstResponder() to give focus to the text field and make the keyboard appear.

    有关如何在某个范围内获取文本的信息，请参阅此答案.

    See this answer for how to get the text at some range.

    • 如何在 Swift 中创建范围

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