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POUITextView attributedText and syntax highlighting
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copied!<h1>Background</h1> <p>So, with iOS 6 an UITextView can take an attributedString, which could be useful for Syntax highlighting.</p> <p>I'm doing some regex patterns in <code>-textView:shouldChangeTextInRange:replacementText:</code> and oftentimes I need to change the color of a word already typed. I see no other options than resetting the attributedText, which takes time.</p> <pre><code>- (BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)text { //A context will allow us to not call -attributedText on the textView, which is slow. //Keep context up to date [self.context replaceCharactersInRange:range withAttributedString:[[NSAttributedString alloc] initWithString:text attributes:self.textView.typingAttributes]]; // […] self.textView.scrollEnabled = FALSE; [self.context setAttributes:self.defaultStyle range:NSMakeRange(0, self.context.length)]; [self refresh]; //Runs regex-patterns in the context textView.attributedText = self.context; self.textView.selectedRange = NSMakeRange(range.location + text.length, 0); self.textView.scrollEnabled = TRUE; return FALSE; } </code></pre> <p>This runs okayish on the simulator, but on an iPad 3 each <code>-setAttributedText</code> takes a few hundreds of milliseconds.</p> <p>I filed a bug to Apple, with the request of being able to mutate the attributedText. It got marked as a duplicate, so I cannot see what they're saying about this.</p> <h1>The question</h1> <p><strong>The more specific question:</strong> How can I change the color of certain ranges in a UITextView, with a large multicolored text, with good enough performance to do it in every <code>shouldReplaceText...</code>?</p> <p><strong>The more broad question:</strong> How do you do syntax highlighting with a UITextView in iOS 6?</p>

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