Assigning AVAudioRecorderDelegate to non UIViewController

Question

I'm creating an iOS application that starts recording audio when a prompt occurs rather than when a button is pressed. Because of this, I've put the AVAudioRecorder in a scheduler object that is called from it's own class. However, when I assign the scheduler as the delegate for the recorder, I get the warning Assigning to 'id<AVAudioRecorderDelegate>' from incompatible type 'LWPScheduler *__strong'. Here is the implementation for the scheduler:

@implementation LWPScheduler
@synthesize tempo;
@synthesize userName;

+(LWPScheduler *)masterScheduler{
    static LWPScheduler *masterScheduler = nil;
    if (masterScheduler == nil)
    {
        masterScheduler = [[self alloc] init];
    }
    return masterScheduler;
}

- (id)init
{
    self = [super init];
    if (self) {
        self.tempo = 120;
        self.userName = @"Tim Burland";

        //recording init
        // Set the audio file
        NSArray *pathComponents = [NSArray arrayWithObjects:
                                   [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject],
                                   @"MyAudioMemo.m4a",
                                   nil];
        NSURL *outputFileURL = [NSURL fileURLWithPathComponents:pathComponents];

        //audio session
        AVAudioSession *session = [AVAudioSession sharedInstance];
        [session setCategory:AVAudioSessionCategoryPlayAndRecord error:nil];

        //recorder settings
        NSMutableDictionary *recordSetting = [[NSMutableDictionary alloc] init];

        [recordSetting setValue:[NSNumber numberWithInt:kAudioFormatMPEG4AAC] forKey:AVFormatIDKey];
        [recordSetting setValue:[NSNumber numberWithFloat:44100.0] forKey:AVSampleRateKey];
        [recordSetting setValue:[NSNumber numberWithInt: 2] forKey:AVNumberOfChannelsKey];

        // Initiate and prepare the recorder
        _recorder = [[AVAudioRecorder alloc] initWithURL:outputFileURL settings:recordSetting error:NULL];
        _recorder.delegate = self; //Incompatible Type Warning Here
        _recorder.meteringEnabled = YES;
        [_recorder prepareToRecord];
    }
    return self;
}

@end

My question is whether I have to migrate the audio handling to the controller for the view the recorder would be contained in. Thanks for your help!

Answer 1

On your interface (or private class extension) tell the compiler that your are conforming to the protocol the delegate expects. For e.g.:

@interface LWPScheduler : NSObject <AVAudioRecorderDelegate>
// ...
@end

The protocol defines required and/or optional methods you may have to implement (Xcode will warn you about the required one). After telling the interface the class confirms to the protocol, _recorder.delegate = self; will just work.