以下内容适用于UITextField和UITextView。

有用的信息

文本字段文本的最开始：

let startPosition: UITextPosition = textField.beginningOfDocument

文本字段文本的末尾：

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)")
}

设定光标位置

为了设置位置，所有这些方法实际上都是使用相同的开始值和结束值来设置范围。

从头开始

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)

在当前光标位置左侧的一个位置

// 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。

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

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

有关

选择所有文字

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

选择文字范围

// 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")

笔记

• 使用textField.becomeFirstResponder()给予重点的文本字段，使键盘出现。