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POCoreText rendering text glitch
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copied!<p>I am working on a new app. I render different documents from an NSAttributedString using Core Text. I am having trouble with strange glitches in the rendering of the text. It doesn't happen with every document. There doesn't seem to be a rhyme or reason to when it appears or not.</p> <p>Here is a cropped screen shot here to demonstrate the problem. </p> <p><img src="https://i.stack.imgur.com/ZqraO.png" alt="Glitch in rendering"></p> <p>Here is a line from the same screenshot that is rendered correctly.</p> <p><img src="https://i.stack.imgur.com/nMDEs.png" alt="Correct rendering"></p> <p><strong>The screenshots are from the same screenshot and the same document.</strong></p> <p>When the problem occurs, there are usually only 2-3 consecutive lines of text that are rendered incorrectly. The rest of the document is fine. </p> <p>Here is the code that I use to render the text in drawRect:</p> <pre><code>CGContextRef context = UIGraphicsGetCurrentContext(); float viewHeight = self.bounds.size.height; CGContextTranslateCTM(context, 0, viewHeight); CGContextScaleCTM(context, 1.0, -1.0); CGContextSetTextMatrix(context, CGAffineTransformMakeScale(1.0, 1.0)); CGMutablePathRef path = CGPathCreateMutable(); CGRect bounds = CGRectMake(PADDING_LEFT, -PADDING_TOP, self.bounds.size.width-20.0, self.bounds.size.height); CGPathAddRect(path, NULL, bounds); CTFramesetterRef framesetter = CTFramesetterCreateWithAttributedString((CFMutableAttributedStringRef)attrString); CTFrameRef frame = CTFramesetterCreateFrame(framesetter, CFRangeMake(0, 0), path, NULL); CFRelease(framesetter); CFRelease(path); CTFrameDraw(frame, context); </code></pre> <p>Any assistance is appreciated!</p> <p><strong>EDIT:</strong> This problem does not appear to exist on the iPhone 4, only on the 3GS that I have for testing.</p> <p>The glitch is always in the middle of a document.</p>

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