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POUIImage within Thread not being Released / Overwritten
 

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    <p>This appears to be the the classic method for scanning images from the iPhone. I have a thread that is dispatched from the main thread to go and scan for Codes. It essentially creates a new UIImage each time then removes it.</p> <pre><code>NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init]; { while (![thread isCancelled]) { #ifdef DEBUG NSLog(@"Decoding Loop"); #endif // [self performSelectorOnMainThread:@selector(updateImageBuffer) withObject:nil waitUntilDone:YES]; CGImageRef cgScreen = UIGetScreenImage(); UIImage *uiimage = [UIImage imageWithCGImage:cgScreen]; if (uiimage){ CGSize size = [uiimage size]; CGRect cropRect = CGRectMake(0.0, 80.0, size.width, 360); // Crop to centre of the screen - makes it more robust #ifdef DEBUG NSLog(@"picked image size = (%f, %f)", size.width, size.height); #endif [decoder decodeImage:uiimage cropRect:cropRect]; } [uiimage release]; CGImageRelease(cgScreen); } } [pool release]; </code></pre> <p>the problem is that the [pool release] causes an ERROR_BAD_EXC (that old classic) and the program bombs. I'm told that there is no need to call [uiimage release] as I havent explicitly allocated a UIImage but this doesn't seem to be the case. If I take that line out, Memory usage goes through the roof and the program quits dues to lack of memory. It appears I can't have this work the way I'd like.</p> <p>Is there a way to create a UIImage "in-place"? I.e, have a buffer that is written to again and again as a UIImage? I suspect that would work?</p> <p><strong>Update!</strong></p> <p>Tried executing the UIKit related calls on the main thread as follows:</p> <pre><code>-(void)performDecode:(id)arg{ // Perform the decoding in a seperate thread. This should, in theory, bounce back with a // decoded or not decoded message. We can quit at the end of this thread. NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init]; { while (![thread isCancelled]) { #ifdef DEBUG NSLog(@"Decoding Loop"); #endif [self performSelectorOnMainThread:@selector(updateImageBuffer) withObject:nil waitUntilDone:YES]; if (uiimage){ CGSize size = [uiimage size]; CGRect cropRect = CGRectMake(0.0, 80.0, 320, 360); // Crop to centre of the screen - makes it more robust #ifdef DEBUG NSLog(@"picked image size = (%f, %f)", size.width, size.height); #endif [decoder decodeImage:uiimage cropRect:cropRect]; } } } [pool drain]; #ifdef DEBUG NSLog(@"finished decoding."); #endif } -(void) updateImageBuffer { CGImageRef cgScreen = UIGetScreenImage(); uiimage = [UIImage imageWithCGImage:cgScreen]; //[uiimage release]; CGImageRelease(cgScreen); } </code></pre> <p>No joy however as EXC_BAD_ACCESS rears its ugly head when one wishes to grab the "Size" of the UIImage</p>
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