Swift attribute for new line in NSAttributedString

Question

I have a UITextView with a lightGray text.

I would like the color to always be set to black with each new line so that I can be sure that the new line is always black regardless of the color of the previous line

For example

This is first line --> foregroundColor.lightgray

\n

_ --> this new empty line must have foregroundColor.black

To do this I tried to change the foregroundColor attribute every time I hit enter (new line \n)

In Coordinator of UITextView

    func textView(_ textView: UITextView, shouldChangeTextIn range: NSRange, replacementText text: String) -> Bool {
        if text == "\n" {
                let customAttrributes : [NSAttributedString.Key: Any] = [
                    NSAttributedString.Key.foregroundColor: UIColor.black
                ]
                if textView.selectedTextRange != nil {
                   textView.textStorage.addAttributes(customAttrributes, range: NSRange(location: textView.selectedRange.location, length: 1))

This return an "Out of bounds" error and I don't understand why. I suppose it is due to the fact that since there is no character, length 1 is considered non-existent. But then is it possible to set the new blank line already with the black text attribute or do you have to wait for some characters to be inserted?

Thanks!

I think the problem is that `textView.selectedRange.location` is probably at the end of the `NSAttributedString`, so when you set a attribute range starting there with a length of 1, you're going past the end - that is, out of bounds. If you back-arrow (or click) to some position earlier in the text and insert a new line there, I would guess that you wouldn't get the error. — Chip Jarred, Oct 15 '22 at 10:47

Bulat Yakupov · Accepted Answer · 2022-10-15T10:54:15.420

1

One of easiest way to do it is to set typingAttributes. You can detect a new line using this answer for example. So let's say what we started printing with .lightGray color. Firstly we set: textView.typingAttributes = [.foregroundColor: UIColor. lightGray]. We should switch to the black color on a start of a new line.

var previousRect = CGRect.zero
func textViewDidChange(_ textView: UITextView) {
    let pos = textView.endOfDocument
    let currentRect = textView.caretRect(for: pos)
    self.previousRect = self.previousRect.origin.y == 0.0 ? currentRect : self.previousRect
    if currentRect.origin.y > self.previousRect.origin.y {
        textView.typingAttributes = [.foregroundColor: UIColor.black]
    }
    self.previousRect = currentRect
}

edited Oct 15 '22 at 10:54

answered Oct 15 '22 at 08:07

Bulat Yakupov

440
4
13

thanks Bulat I had already tried to set the black color already in the textStorage. In reality, when a new line is created within an already set attribute (foregroundColor.lightgray) the text wraps but does not open a new attribute, but simply continues with the attribute that already exists in the previous line. Trying to create a new one as you can see from my example, it is not possible due to an "out of bonds" error. Thanks | – Stefano Vet Oct 15 '22 at 08:22
I added one more idea which can actually be a better solution for you :) – Bulat Yakupov Oct 15 '22 at 08:25
I have already used shouldChangeTextIn however as you see in the example. The problem is not intercepting the new line but unfortunately I don't think it is possible to add an attribute to a new line that is still empty. Thanks so much! – Stefano Vet Oct 15 '22 at 08:38
1

In order to set attributes for text your are going to insert you need to use typingAttributes – Bulat Yakupov Oct 15 '22 at 08:41
Thanks Bulat!! Simply add textView.typingAttributes = [NSAttributedString.Key.foregroundColor:UIColor.black] in shouldChangeTextIn solves the problem! If you want to answer, so i can set the answer as accepted! – Stefano Vet Oct 15 '22 at 09:03
No problem. Yes, please :) – Bulat Yakupov Oct 15 '22 at 09:04
ok. I await your response then. Thank you again – Stefano Vet Oct 15 '22 at 09:09
Stefano, I updated my answer :) – Bulat Yakupov Oct 15 '22 at 11:31
in my example I just removed .addAttribute and added .typingAttributes. Update your replay like this if you agree: func textView (_ textView: UITextView, shouldChangeTextIn range: NSRange, replacementText text: String) -> Bool { if text == "\ n" { textView.typingAttributes = [NSAttributedString.Key.foregroundColor: UIColor.black] – Stefano Vet Oct 15 '22 at 11:50
\n is not a convenient way to check for a new line. New line can appear without that if there are too many characters. So I will keep my answer as is, but you can write your code as you wish. – Bulat Yakupov Oct 15 '22 at 12:08

score 0 · Answer 2 · answered Oct 15 '22 at 07:13

0

This is an example for two line with different text and textColor in NSAttributedString:

 let attributedString = NSMutableAttributedString(attributedString: NSAttributedString(string: "First Line", attributes: [.font: UIFont.systemFont(ofSize: 16, weight: .semibold), .foregroundColor: UIColor.lightGray]))
    attributedString.append(NSAttributedString(string: "Second Line", attributes: [.foregroundColor: UIColor.black, .font: UIFont.systemFont(ofSize: 16, weight: .semibold)]))
textView.attributedText = attributedString

answered Oct 15 '22 at 07:13

Fabio

5,432
4
22
24

The problem is that I don't know the second line text being a text editor. I should always start with black even if the row is empty. It should always be borne in mind that even if I divide a gray sentence, the part that goes into the new line should become black. Thanks! – Stefano Vet Oct 15 '22 at 07:22

Swift attribute for new line in NSAttributedString

2 Answers2