Application crash on -[__NSCFSet bytes]: unrecognized selector sent to instance ""? - iphone

Question

I developing an application that application well worked for me my XCode version is 4.2.1 and iOS version is 5.0 ARC enable code. My process is i showing a bunch of YouTube videos in tableview using web service. I cache those video Icon in my directory. When i sending that application for apple review... application going crash there, the crash report is following,
Exception Type: EXC_CRASH (SIGABRT)
Exception Codes: 0x00000000, 0x00000000
Crashed Thread: 2
Application Specific Information:
*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[__NSCFSet bytes]: unrecognized selector sent to instance 0x27b300'
*** First throw call stack:
(0x3502e88f 0x36455259 0x35031a9b 0x35030915 0x34f8b650 0x34f7da4d 0x3587f2b9 0x3587ef31 0x3587ee9d 0x321102ab 0x321101c7 0xe36dd 0x31053c59 0x3105f7bb 0x36cd9dfb 0x36cd9cd0)
Thread 2 name: Dispatch queue: com.apple.root.default-priority
Thread 2 Crashed:
0 libsystem_kernel.dylib 0x34e2232c __pthread_kill + 8
1 libsystem_c.dylib 0x36d1e208 pthread_kill + 48
2 libsystem_c.dylib 0x36d17298 abort + 88
3 libc++abi.dylib 0x309e3f64 abort_message + 40
4 libc++abi.dylib 0x309e1346 _ZL17default_terminatev + 18
5 libobjc.A.dylib 0x36455350 _objc_terminate + 140
6 libc++abi.dylib 0x309e13be _ZL19safe_handler_callerPFvvE + 70
7 libc++abi.dylib 0x309e144a std::terminate() + 14
8 libc++abi.dylib 0x309e2798 __cxa_throw + 116
9 libobjc.A.dylib 0x36455290 objc_exception_throw + 88
10 CoreFoundation 0x35031a94 -[NSObject doesNotRecognizeSelector:] + 168
11 CoreFoundation 0x3503090e ___forwarding___ + 294
12 CoreFoundation 0x34f8b648 _CF_forwarding_prep_0 + 40
13 CoreFoundation 0x34f7da46 CFDataGetBytePtr + 90
14 ImageIO 0x3587f2b2 CGImageReadGetBytePointer + 30
15 ImageIO 0x3587ef2a _CGImageSourceBindToPlugin + 86
16 ImageIO 0x3587ee96 CGImageSourceGetCount + 50
17 UIKit 0x321102a4 _UIImageRefFromData + 124
18 UIKit 0x321101c0 -[UIImage initWithData:] + 52
19 MyAppName 0x000e36d6 __37-[JMImageCache imageForURL:delegate:]_block_invoke_0 + 142
20 libdispatch.dylib 0x31053c52 _dispatch_call_block_and_release + 6
21 libdispatch.dylib 0x3105f7b4 _dispatch_worker_thread2 + 256
22 libsystem_c.dylib 0x36cd9df4 _pthread_wqthread + 288
23 libsystem_c.dylib 0x36cd9cc8 start_wqthread + 0
Now my coding part in application ,
On Table view data source method
if(![[JMImageCache sharedCache] isImageExistInCache: cell.videoThumbnailImageLink]){
[cell.activityIndicator startAnimating];
cell.videoThumbnail.image = [[JMImageCache sharedCache] imageForURL:cell.videoThumbnailImageLink delegate:cell];
}
else{
[cell.activityIndicator stopAnimating];
[cell.activityIndicator removeFromSuperview];
cell.videoThumbnail.image = [[JMImageCache sharedCache] imageFromDiskForURL:cell.videoThumbnailImageLink];
}
And at custom cell of that tableview,
#pragma mark - JMImageCacheDelegate Methods
- (void) cache:(JMImageCache *)c didDownloadImage:(UIImage *)i forURL:(NSString *)url {
if([url isEqualToString:self.videoThumbnailImageLink]) {
self.imageView.image = i;
[self setNeedsLayout];
}
[self.activityIndicator stopAnimating];
[self.activityIndicator removeFromSuperview];
}
In JMImageCache library code block,
- (UIImage *) imageForURL:(NSString *)url delegate:(id<JMImageCacheDelegate>)d {
if(!url) {
return nil;
}
id returner = [super objectForKey:url];
if(returner) {
return returner;
} else {
UIImage *i = [self imageFromDiskForURL:url];
if(i) {
[self setImage:i forURL:url];
return i;
}
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
__unsafe_unretained NSData *data = [NSData dataWithContentsOfURL:[NSURL URLWithString:url]];
UIImage *i = [[UIImage alloc] initWithData:data];
__unsafe_unretained NSString* cachePath = cachePathForURL(url);
NSInvocation* writeInvocation = [NSInvocation invocationWithMethodSignature:[self methodSignatureForSelector:#selector(writeData:toPath:)]];
[writeInvocation setTarget:self];
[writeInvocation setSelector:#selector(writeData:toPath:)];
[writeInvocation setArgument:&data atIndex:2];
[writeInvocation setArgument:&cachePath atIndex:3];
[self performDiskWriteOperation:writeInvocation];
[self setImage:i forURL:url];
dispatch_async(dispatch_get_main_queue(), ^{
if(d) {
if([d respondsToSelector:#selector(cache:didDownloadImage:forURL:)]) {
[d cache:self didDownloadImage:i forURL:url];
}
}
});
});
return nil;
}
}
Thanks.

Answer 1

You have a memory problem. The hint is, that the variable which points to 0x27b300 in memory now contains a __NSCFSet (otherwise known as an NSSet). Make sure you're not using a variable which hasn't been nil'd out or is weak when it should be strong.

Answer 2

Your data is being released and deallocated before it's used, so when CoreGraphics calls -bytes on it, it's no longer there (and in this case, an NSSet has been allocated in its place).
Presumably this is because you declared it as __unsafe_unretained.