[Crash] NSInvalidArgumentException at +[UIImage(Additions) add_cachedImageWithDescriptors:]

[Bluezen]

Hello,
First of all thank you for the nice library!

I have got an app that use it in production but unfortunately Fabric reports many crashes from users at line 413:

+ (UIImage*)add_cachedImageWithDescriptors:(NSDictionary*)descriptors
{
    return [[self add_cache] objectForKey:[self add_keyForImageWithDescriptors:descriptors]];
}

with the exception:

Fatal Exception: NSInvalidArgumentException

-[__NSCFString objectForKey:]: unrecognized selector sent to instance 0x148027b50

How come does [self add_cache] could be an NSString? Do you have any idea how to prevent this crash to happen ? Should we re-think the way _imageCache is initialized?

+ (NSCache*)add_cache
{
    if (!_imageCache)
        _imageCache = [[NSCache alloc] init];

    return _imageCache;
}

To give you more insight, I make use of

[UIImage add_imageWithGradient:(...) size:(...) direction:ADDImageGradientDirectionVertical];

in a background thread, could that be the reason why the crash is random? (I can't seem to reproduce it reliably). Should I make the call only from the main thread and would that be enough to never encounter the crash again?

[vilanovi]

Hello,

Thanks for reporting the issue. This problem has never happened to me before. However, I guess that the current implementation is not thread safe when creating the NSCache instance.

Therefore, I've replaced the current implementation for a dispatch_once block. This should prevent any thread issue when accessing the +add_cache method.

You will find the changes in version 2.1.1 (already available in Cocoa Pods).

For now I will close the issue, however if the problem reappears, please let me know and I'll reopen it.

Thanks!

[Bluezen]

Thank you! I will let you know if the problem reappears!