NSInvalidArgumentException in objective-c call

Question

Sorry, only my second day working with an inherited objective-c project under flutter.

I've just a new method to the obj-c code and its throwing an exception.

I'm guessing there is something wrong with my method signature.

When I inspect the path and callbackUuid variables they have the expected values before the call is made.

The code is being called from flutter/dart but I don't think that has anything to do with the problem.

NSInvalidArgumentException  
unrecognized selector sent to instance xxxx
[NSObject(NSObject) doesNotRecognizeSelector]
_CF_forwarding_prep_0
SoundPlayerManger handlerMethodCall:result

The calling code:

NSString* path = (NSString*)call.arguments[@"path"];
                NSString* callbackUuid = (NSString*)call.arguments[@"callbackUuid"];
                [aSoundPlayer getDuration:path callbackUuid: callbackUuid result:result];

The declaration

- (void)getDuration: (NSString*_Nonnull)path callbackUuid:(NSString*_Nonnull)callbackUuid  result:(FlutterResult _Nonnull )result;

The method I'm calling:

- (void)getDuration: (NSString*)path callbackUuid:(NSString*)callbackUuid  result:(FlutterResult)result
{
        /// let the dart code resume whilst we calculate the duratin.
        result(@"queued");
        NSLog(@"getDuration queued");

        NSURL *afUrl = [NSURL fileURLWithPath:path];
        AudioFileID fileID;
        NSLog(@"Call AudioFileOpenUrl");
        OSStatus status = AudioFileOpenURL((__bridge CFURLRef)afUrl, kAudioFileReadPermission, 0, &fileID);
        Float64 outDataSize = 0;
        UInt32 thePropSize = sizeof(Float64);
        status = AudioFileGetProperty(fileID, kAudioFilePropertyEstimatedDuration, &thePropSize, &outDataSize);
        AudioFileClose(fileID);

        NSLog(@"%@", [NSString stringWithFormat:@"getDuration status%d", (int)status]);

        if (status == kAudioServicesNoError)
        {
                int milliseconds = outDataSize * 1000;

                NSString* args = [NSString stringWithFormat:@"{\"callbackUuid\": \"%@\", \"milliseconds\": %d}"
                                ,callbackUuid
                                , milliseconds ];
                [self invokeCallback:@"durationResults" stringArg:args];
        }
        else
        {
                /// danger will robison, danger
            NSString* args = [NSString stringWithFormat:@"{\"callbackUuid\": \"%@\", \"description\": \"%d\"}"
                              , callbackUuid
                              , (int)status ];
                [self invokeCallback:@"onError" stringArg:args];

        }
        
}

Answer 1

So turns out my method signature was correct it was just that the instance hadn't been created it.

Great message team!