How can I make a UITextView layout text the same as a UILabel?

Question

I have a UILabel that I need to convert to a UITextView because reasons. When I do this, the text is not positioned the same, despite using the same (custom) font.

I found that if I set:

textView.textContainer.lineFragmentPadding = 0;
textView.textContainerInset = UIEdgeInsetsZero;

This gets the text very close, but if I superimpose the UITextView over top of the UILabel, I see the text positioning get farther apart with each new line.

The UILabel is green, the UITextView is black. This is using NSParagraphStyle to set min and max line height to 15.

I've played with setting the paragraph style and min/max line height, but I haven't been able to match it exactly. I'm not a printer, so I don't necessarily understand all of the font related terms in the documentation for NSLayoutManager and NSTextContainer and all that.

I only need to support iOS 7 and up.

I'm not going to switch to some crazy CoreText-based custom widget or use some random third party library. I'm okay with close enough if I have to. But it seems like there should be some combination of random properties to make them layout the same.

Answer 1

I took the solution for line spacing found at this link and applied it to your issue. I managed to get it incredibly close by adjusting the lineSpacing property. I tested with HelveticaNeue size 13 and managed to get it to line up as shown in the screen shot below.

textView.textContainer.lineFragmentPadding = 0;
textView.textContainerInset = UIEdgeInsetsZero;

NSMutableParagraphStyle *paragraphStyle = [[NSMutableParagraphStyle alloc] init];

paragraphStyle.lineSpacing = -0.38;

NSDictionary *attrsDictionary =
@{ NSFontAttributeName: [UIFont fontWithName:@"HelveticaNeue" size:13.0f],
 NSParagraphStyleAttributeName: paragraphStyle};

textView.attributedText = [[NSAttributedString alloc] initWithString:textView.text attributes:attrsDictionary];

Answer 2

I've been able to successfully 'impersonate' a non-editable multiline UILabel (as it happens, in a UITableViewCell subclass) with an equivalent editable multiline UITextView using the following :

_textView = UITextView.new;
_textView.font = _label.font;
_textView.textColor = _label.textColor;
_textView.textAlignment = _label.textAlignment;
_textView.backgroundColor = UIColor.clearColor;
_textView.textContainer.lineFragmentPadding = 0;
_textView.textContainerInset = UIEdgeInsetsZero;

and to make it behave well when doing actual edits, add the following to your UITextViewDelegate:

- (void)textViewDidChange:(UITextView *)textView
{
    ...
    [textView scrollRangeToVisible:NSMakeRange(textView.text.length, 0)];
    [textView scrollRectToVisible:[textView caretRectForPosition:textView.endOfDocument] animated:NO];
}