Core Text in UITableviewCell's content overlapping and repeating and superimpose on the other cells

Question

I am using Core Text to add text to UITableviewCell\'s content but arabic content seems to be overlapping and repeating itself as I scroll and superimpose on the other cells

Answer 1

I was facing the same problem until I read up about NSAttributedStrings (made available in iOS 6) on this tutorial here.

The following code will solve your issue:

NSMutableAttributedString *attributedString = [[NSMutableAttributedString alloc] initWithString:info.text attributes:@{ NSFontAttributeName : [UIFont fontWithName:@"Scheherazade" size:32], NSLigatureAttributeName: @2}];

cell.textLabel.attributedText = attributedString;

Out of curiosity, would I be correct to say that you opted to use CoreText because of difficulties in rendering embedded arabic fonts? I ventured the guess because I was attempting to use a similar method as you have done in your code when faced with that exact problem for a Quran app that I'm currently developing. If this so then I can confirm that using NSAttributedString also solves the problem. If you notice in the code above I've also set the NSLigatureAttributeName to 2 which according to the official Apple Class Reference Documentation means 'all ligatures'. Just note that this is something that I'm currently testing and I have yet to see the effects of this but I know that ligatures is a common problem in the rendering of some arabic fonts on certain platforms.

While on the subject, another common problem you may be facing is the line-spacing of arabic text and the slight overlapping of multi-line text and I've found that NSAttributedString can also be a good solution when used together with NSParagraphStyle (Hooray again for NSAttributedString!). Simply modify the above code as below:

NSMutableAttributedString *attributedString = [[NSMutableAttributedString alloc] initWithString:info.text attributes:@{ NSFontAttributeName : [UIFont fontWithName:@"Scheherazade" size:32], NSLigatureAttributeName: @2}];

NSMutableParagraphStyle *paragraphStyle = [[NSMutableParagraphStyle alloc] init];
[paragraphStyle setLineSpacing:20];
[attributedString addAttribute:NSParagraphStyleAttributeName value:paragraphStyle range:NSMakeRange(0, [info.text length])];

cell.textLabel.attributedText = attributedString;

Hope this helps you or anyone else out there!

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EDIT - Adding this helpful post on Common Mistakes With Adding Custom Fonts to Your iOS App for reference as a "checklist" when adding custom fonts on iOS.