xcode 如何在 UITextView 中的每个新行中添加无序列表或项目符号点

How do I add an unordered list or a bullet point every new line in a UITextView

提问by Horray

So basically I want to add an unordered list to a UITextView. And to another UITextViewI want to add an ordered list.

所以基本上我想将一个无序列表添加到UITextView. 另一个UITextView我想添加一个有序列表。

I tried using this code, but it only gave me a bullet point after the first time the user presses enter, (not any more than that,) and I can't even backspace it.

我尝试使用此代码，但在用户第一次按下 Enter 后，它只给了我一个要点，（仅此而已），我什至无法退格它。

- (void)textViewDidChange:(UITextView *)textView
{
    if ([myTextField.text isEqualToString:@"\n"]) {
        NSString *bullet = @"\u2022";
        myTextField.text = [myTextField.text stringByAppendingString:bullet];
    }
}

If you only find a way performing it with Swift then feel free to post a Swift version of the code.

如果您只找到一种使用 Swift 执行它的方法，那么请随时发布代码的 Swift 版本。

回答by Lyndsey Scott

The problem is that you're using

问题是你正在使用

if ([myTextField.text isEqualToString:@"\n"]) {

as your conditional, so the block executes if the entirety of your myTextField.textequals "\n". But the entirety of your myTextField.textonly equals "\n" if you haven't entered anything but"\n". That's why right now, this code is only working "the first time the user presses enter"; and when you say "I can't even backspace it," the problem is actually that the bullet point's being re-addedwith the call to textViewDidChange:since the same conditional is still being met.

作为你的条件，所以如果你的整体myTextField.text等于“\n” ，块就会执行。但是，myTextField.text如果您除了“\n”之外没有输入任何内容，则您的only的整体等于“\n”。这就是为什么现在，这段代码只在“用户第一次按下回车键时”起作用；当你说“我什至不能退格它”时，问题实际上是子弹点被重新添加到调用中，textViewDidChange:因为仍然满足相同的条件。

Instead of using textViewDidChange:I recommend using shouldChangeTextInRange:in this case so you can know what that replacement text is no matter it's position within the UITextViewtext string. By using this method, you can automatically insert the bullet point even when the newline is entered in the middle of the block of text... For example, if the user decides to enter a bunch of info, then jump back up a few lines to enter some more info, then tries to press newline in between, the following should still work. Here's what I recommend:

textViewDidChange:我建议shouldChangeTextInRange:在这种情况下使用而不是使用，这样您就可以知道替换文本是什么，无论它在UITextView文本字符串中的位置。通过使用这种方法，即使在文本块的中间输入换行符，您也可以自动插入项目符号...例如，如果用户决定输入一堆信息，然后跳回几行输入更多信息，然后尝试在中间按换行符，以下应该仍然有效。这是我的建议：

- (BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)text {

    // If the replacement text is "\n" and the
    // text view is the one you want bullet points
    // for
    if ([text isEqualToString:@"\n"]) {

        // If the replacement text is being added to the end of the
        // text view, i.e. the new index is the length of the old
        // text view's text...
        if (range.location == textView.text.length) {
            // Simply add the newline and bullet point to the end
            NSString *updatedText = [textView.text stringByAppendingString:@"\n\u2022 "];
            [textView setText:updatedText];
        }

        // Else if the replacement text is being added in the middle of
        // the text view's text...
        else {

            // Get the replacement range of the UITextView
            UITextPosition *beginning = textView.beginningOfDocument;
            UITextPosition *start = [textView positionFromPosition:beginning offset:range.location];
            UITextPosition *end = [textView positionFromPosition:start offset:range.length];
            UITextRange *textRange = [textView textRangeFromPosition:start toPosition:end];

            // Insert that newline character *and* a bullet point
            // at the point at which the user inputted just the
            // newline character
            [textView replaceRange:textRange withText:@"\n\u2022 "];

            // Update the cursor position accordingly
            NSRange cursor = NSMakeRange(range.location + @"\n\u2022 ".length, 0);
            textView.selectedRange = cursor;

        }
        // Then return "NO, don't change the characters in range" since
        // you've just done the work already
        return NO;
    }

    // Else return yes
    return YES;
}

回答by KuboAndTwoStrings

Just in case, anyone was looking for a Swift 2.x solution to the same problem, here's a solution:

以防万一，有人正在寻找针对同一问题的 Swift 2.x 解决方案，这里有一个解决方案：

func textView(textView: UITextView, shouldChangeTextInRange range: NSRange, replacementText text: String) -> Bool {
    // If the replacement text is "\n" and the
    // text view is the one you want bullet points
    // for
    if (text == "\n") {
        // If the replacement text is being added to the end of the
        // text view, i.e. the new index is the length of the old
        // text view's text...


        if range.location == textView.text.characters.count {
            // Simply add the newline and bullet point to the end
            var updatedText: String = textView.text!.stringByAppendingString("\n \u{2022} ")
            textView.text = updatedText
        }
        else {

            // Get the replacement range of the UITextView
            var beginning: UITextPosition = textView.beginningOfDocument
            var start: UITextPosition = textView.positionFromPosition(beginning, offset: range.location)!
            var end: UITextPosition = textView.positionFromPosition(start, offset: range.length)!
            var textRange: UITextRange = textView.textRangeFromPosition(start, toPosition: end)!
            // Insert that newline character *and* a bullet point
            // at the point at which the user inputted just the
            // newline character
            textView.replaceRange(textRange, withText: "\n \u{2022} ")
            // Update the cursor position accordingly
            var cursor: NSRange = NSMakeRange(range.location + "\n \u{2022} ".length, 0)
            textView.selectedRange = cursor
        }

        return false


    }
    // Else return yes
    return true
}