在 UITextView Swift 3 中创建编号列表 [英] Creating A Numbered List In UITextView Swift 3
问题描述
我正在尝试根据用户输入到 UITextView 的信息制作一个编号列表.例如,
I am trying to make a numbered list out of the information the user inputs into a UITextView. For example,
- 列出第一项
- 列出第二项
- 列出项目三
这是我尝试过的代码,但没有给我想要的效果.var currentLine: Int = 1
Here is the code that I have tried but does not give me the desired effect. var currentLine: Int = 1
func textView(_ textView: UITextView, shouldChangeTextIn range: NSRange, replacementText text: String) -> Bool {
// Add "1" when the user starts typing into the text field
if (textView.text.isEmpty && !text.isEmpty) {
textView.text = "\(currentLine). "
currentLine += 1
}
else {
if text.isEmpty {
if textView.text.characters.count >= 4 {
let str = textView.text.substring(from:textView.text.index(textView.text.endIndex, offsetBy: -4))
if str.hasPrefix("\n") {
textView.text = String(textView.text.characters.dropLast(3))
currentLine -= 1
}
}
else if text.isEmpty && textView.text.characters.count == 3 {
textView.text = String(textView.text.characters.dropLast(3))
currentLine = 1
}
}
else {
let str = textView.text.substring(from:textView.text.index(textView.text.endIndex, offsetBy: -1))
if str == "\n" {
textView.text = "\(textView.text!)\(currentLine). "
currentLine += 1
}
}
}
return true
}
如此处建议:如何在快速按下返回键时在 UITextview 上进行自动编号但没有成功.
as suggested here: How to make auto numbering on UITextview when press return key in swift but had no success.
非常感谢任何帮助.
推荐答案
您可以子类化 UITextView,覆盖方法 willMove(toSuperview,并使用选择器为 UITextViewTextDidChange 添加一个观察者,该选择器将您的文本分成几行并相应地对其进行编号.尝试像这样:
You can subclass UITextView, override method willMove(toSuperview and add an observer for UITextViewTextDidChange with a selector that break up your text into lines enumerating and numbering it accordingly. Try like this:
class NumberedTextView: UITextView {
override func willMove(toSuperview newSuperview: UIView?) {
frame = newSuperview?.frame.insetBy(dx: 50, dy: 80) ?? frame
backgroundColor = .lightGray
NotificationCenter.default.addObserver(self, selector: #selector(textViewDidChange), name: .UITextViewTextDidChange, object: nil)
}
func textViewDidChange(notification: Notification) {
var lines: [String] = []
for (index, line) in text.components(separatedBy: .newlines).enumerated() {
if !line.hasPrefix("\(index.advanced(by: 1))") &&
!line.trimmingCharacters(in: .whitespaces).isEmpty {
lines.append("\(index.advanced(by: 1)). " + line)
} else {
lines.append(line)
}
}
text = lines.joined(separator: "\n")
// this prevents two empty lines at the bottom
if text.hasSuffix("\n\n") {
text = String(text.characters.dropLast())
}
}
}
<小时>
import UIKit
class ViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
let textView = NumberedTextView()
view.addSubview(textView)
}
}
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