以下内容同时适用于UITextField和UITextView.

Useful information

文本字段文本的最开始位置:

let startPosition: UITextPosition = textField.beginningOfDocument

文本字段文本的最末尾:

let endPosition: UITextPosition = textField.endOfDocument

当前选定的范围:

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

为了设置位置，所有这些方法实际上都是使用相同的起始值和结束值设置范围.

To the beginning个

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

To the end个

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

To one position to the left of the current cursor position个

// 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个

从开头开始，向右移动5个字符.

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个

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

Select a range of text个

// 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

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

• 有关如何在某个范围内获取文本的信息，请参见this answer.

See also

• How to Create a Range in Swift