StackOverflow2013

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POUIGraphicsGetImageFromCurrentImageContext memory leak with previews
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copied!<p>I'm trying to create previews images of pages in a PDF but I have some problems with the release of memory.</p> <p>I wrote a simple test algorithm that cycles on the problem, <strong>the app crashes near the 40th iteration</strong>:</p> <pre><code>NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES); NSString *documentsDirectory = [paths objectAtIndex:0]; NSString *pdfPath = [documentsDirectory stringByAppendingPathComponent:@"myPdf.pdf"]; CFURLRef url = CFURLCreateWithFileSystemPath( NULL, (CFStringRef)pdfPath, kCFURLPOSIXPathStyle, NO ); CGPDFDocumentRef myPdf = CGPDFDocumentCreateWithURL( url ); CFRelease (url); CGPDFPageRef page = CGPDFDocumentGetPage( myPdf, 1 ); int i=0; while(i < 1000){ UIGraphicsBeginImageContext(CGSizeMake(768,1024)); CGContextRef context = UIGraphicsGetCurrentContext(); CGContextSetRGBFillColor(context, 1.0,1.0,1.0,1.0); CGContextFillRect(context,CGRectMake(0, 0, 768, 1024)); CGContextSaveGState(context); CGContextTranslateCTM(context, 0.0, 1024); CGContextScaleCTM(context, 1.0, -1.0); CGContextDrawPDFPage(context, page); CGContextRestoreGState(context); // -------------------------- // The problem is here (without this line the application doesn't crash) UIImageView *backgroundImageView1 = [[UIImageView alloc] initWithImage:UIGraphicsGetImageFromCurrentImageContext()]; // -------------------------- UIGraphicsEndImageContext(); [backgroundImageView1 release]; NSLog(@"Loop: %d", i++); } CGPDFDocumentRelease(myPdf); </code></pre> <p>The above-mentioned line seems to generate a memory leak, however, <em>instruments</em> doesn't show memory problems;</p> <p>Can I escape from this kind of mistake?someone can explain me in which way? Are there other ways to show previews of a pdf?</p> <p><strong>UPDATE</strong></p> <p>I think the problem isn't the release of <code>UIImage</code> created by the method <code>UIGraphicsGetImageFromCurrentImageContext()</code> but the release of <code>UIImageView</code> created with this autorelease image.</p> <p>I have divided the line of code in three steps:</p> <pre><code>UIImage *myImage = UIGraphicsGetImageFromCurrentImageContext(); UIImageView *myImageView = [[UIImageView alloc] init]; [myImageView setImage: myImage]; // Memory Leak </code></pre> <p>The first and second lines doesn't create memory leaks so I think that the method UIGraphicsGetImageFromCurrentImageContext is not the problem.</p> <p>I also tried as follows but the problem persists:</p> <pre><code>UIImageView *myImageView = [[UIImageView alloc] initWithImage:myImage]; </code></pre> <p>I think there is a memory leak in the release of a UIImageView that contains a UIImage with the autorelease property.</p> <p>I tried to write my object UIImageView inheriting a UIView as explained in this <a href="https://stackoverflow.com/questions/4644912/iphone-uiimageview-setimage-leaks">thread</a>.</p> <p>This solution works but isn't very elegant, it's a workaround, I would prefer to use the object UIImageView solving the memory problem.</p>

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