Question

I’m taking a photo with my app, the delegate method is called, the Image is saved in the library, but I have a crash error in the log :

*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '+[NSInvocation invocationWithMethodSignature:]: method signature argument cannot be nil'
*** Call stack at first throw:
(
    0   CoreFoundation                      0x33ac0987 __exceptionPreprocess + 114
    1   libobjc.A.dylib                     0x3347b49d objc_exception_throw + 24
    2   CoreFoundation                      0x33a6b05d +[NSInvocation invocationWithMethodSignature:] + 340
    3   PhotoLibrary                        0x3038da11 __-[PLAssetsSaver _createWriteImageCompletionBlockWithImage:target:selector:contextInfo:]_block_invoke_1 + 96
    4   PhotoLibrary                        0x3038d7cd __-[PLAssetsSaver _saveImage:imageData:properties:completionBlock:]_block_invoke_2 + 56
    5   PhotoLibrary                        0x3038de87 __-[PLAssetsSaver queueJobData:requestEnqueuedBlock:completionBlock:imagePort:previewImagePort:]_block_invoke_2 + 122
    6   libSystem.B.dylib                   0x33c32680 _dispatch_call_block_and_release + 20
    7   libSystem.B.dylib                   0x33c32e38 _dispatch_main_queue_callback_4CF + 220
    8   CoreFoundation                      0x33a482ab __CFRunLoopRun + 1334
    9   CoreFoundation                      0x33a47c87 CFRunLoopRunSpecific + 230
    10  CoreFoundation                      0x33a47b8f CFRunLoopRunInMode + 58
    11  GraphicsServices                    0x33b0e4ab GSEventRunModal + 114
    12  GraphicsServices                    0x33b0e557 GSEventRun + 62
    13  UIKit                               0x32099329 -[UIApplication _run] + 412
    14  UIKit                               0x32096e93 UIApplicationMain + 670
    15  MySoPrettyApp                       0x00002737 main + 82
    16  MySoPrettyApp                       0x000026e0 start + 40
)
terminate called after throwing an instance of 'NSException'

My code is the following :

- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info {
    UIImage *pickedImage = [[info objectForKey:UIImagePickerControllerOriginalImage] retain];
    UIImageWriteToSavedPhotosAlbum (pickedImage, self, @selector(photoSaved:::), nil);
}

-(void)photoSaved:(UIImage*)image didFinishSavingWithError:(NSError*)error contextInfo:(void*)contextInfo {
    if(!error){
        NSLog(@"Photo saved to library!");
    } else{
        NSLog(@"Saving failed :(");
    }
}

pickedImage is not nil.
The photoSaved method is declared in the .h
I also tried with @selector(photoSaved:) and @selector(photoSaved).

What is the problem ?

Answer 1

The proper way to get the selector is as follows, since argument names are also a part of the method name:

 @selector(photoSaved:didFinishSavingWithError:contextInfo:)