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 以及如何使用它的光标位置。我发现了一些关系Objective-C的答案，如

• 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

<但是，由于我正在使用Swift，我想学习如何获取当前光标位置并在Swift中设置它。

以下答案是结果来自Objective-C的实验和翻译。

解决方案

此答案已针对Swift 3进行了更新

以下内容适用于 UITextField 和 U ITextView 。

有用信息

文本字段文本的开头：

 让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：

 让selectedRange：UITextRange？ = textField.selectedTextRange 
  

获取光标位置

 如果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设置了一个具有相同开始和结束值的范围。

从头开始

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

到最后

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

当前光标位置左侧的一个位置

  //仅当当前选中时范围
如果让selectedRange = textField.selectedTextRange {
 
 //并且仅当新位置有效时才
如果让newPosition = textField.position（来自：selectedRange.start，offset） ：-1）{
 
 //设置新位置
 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。

  let arbitraryValue：Int = 5 
如果让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）
  

选择一系列文字

  //范围：3到7 
让startPosition = textField.position（from：textField.beginningOfDocument，offset：3）
让endPosition = textField.position（from：textField.beginningOfDocument，offset：7）
 
如果startPosition！= nil&& endPosition！= nil {
 textField.selectedTextRange = textField.textRange（from：startPosition！，to：endPosition！）
} 
  

在当前光标位置插入文字

  textField .insertText（你好）
  

注释

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




• 请参阅此答案，了解如何在某个范围内获取文字。

参见

• 如何在Swift中创建范围

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

• Getting the cursor position of UITextField in ios
• Control cursor position in UITextField
• UITextField get currently edited word

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

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

解决方案

This answer has been updated for Swift 3

The following content applies to both UITextField and UITextView.

Useful information

The very beginning of the text field text:

let startPosition: UITextPosition = textField.beginningOfDocument

The very end of the text field text:

let endPosition: UITextPosition = textField.endOfDocument

The currently selected range:

let selectedRange: UITextRange? = textField.selectedTextRange

Get cursor position

if let selectedRange = textField.selectedTextRange {

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

    print("\(cursorPosition)")
}

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.

To the beginning

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

To the end

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

To one position to the left of the current cursor position

// 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)
    }
}

To an arbitrary position

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)
}

Related

Select all text

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

Select a range of text

// 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!)
}

Insert text at the current cursor position

textField.insertText("Hello")

Notes

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

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

See also

• How to Create a Range in Swift

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