Adding Key-Value Observing to PubNub

1.h

[sender addObserver: self
  forKeyPath:key
    options:NSKeyValueObservingOptionNew
    context:NULL];

2.h

a = [[AutoUpdateImplementation alloc] init];
    keyChannel = [NSString stringWithString: channel];
    if(i == 0) {
        [a subscribeToChannelWithUpdates:sender
                                    onChannel:@"Ajan"
                                 forKeys:keys withErrorCallback:f];
        i++;
    }
    else {
        [AutoUpdateErrorHandling printWarningForFunction:@"subscribeToChannelWithUpdates" forFile:@"PubNubKeyUpdate" withMessage:@"Repeated attempts to subscribe not allowed"];
    }

3.h

printFunction = f;
    serverChannel = [PNChannel channelWithName:channel shouldObservePresence:YES];
    [PubNub subscribeOnChannel:serverChannel];
    keysToBeUpdated = [[NSArray alloc] initWithArray: keys];
    sourceOfKeys = sender;
        for(id key in keysToBeUpdated) {
            if ([key rangeOfString:@"text"].location == NSNotFound) {
                [AutoUpdateErrorHandling printWarningForFunction:@"subscribeToChannelWithUpdates" forFile:@"AutoUpdateImplementation" withMessage:[@" .text not found in key " stringByAppendingString: key]];
            }
            ….
        }

4.h

[[PNObservationCenter defaultCenter] addMessageReceiveObserver:self
     withBlock:^(PNMessage *message) {
     NSDictionary *messageDict = message.message;
     if([[messageDict objectForKey: @"type"] isEqualToString: @"update"]) {
     NSString *key = [messageDict objectForKey: @"key"];
    NSString *value = [messageDict objectForKey: @"value"];

    [self unregisterForChangeNotification:key sender:sender];
    @try {
      [sender setValue:value forKeyPath:key];
    }
    @catch(NSException *e) {
    printFunction();
    [AutoUpdateErrorHandling printErrorForFunction:@"subscribeToChannelWithUpdates" forFile:@"AutoUpdateImplementation" withMessage:[@"Key sent to application is not key-value coding compliant./nException name: " stringByAppendingString: e.name]];

  
    }
      @try {
        [sender addObserver: self
           forKeyPath:key
             options:NSKeyValueObservingOptionNew
                context:NULL];
              }
                @catch(NSException *e) {
                printFunction();
                [AutoUpdateErrorHandling printErrorForFunction:@"subscribeToChannelWithUpdates" forFile:@"AutoUpdateImplementation" withMessage:[@"Add observer received an unknown key./nException name: " stringByAppendingString: e.name]];
                                                                         
        }
 }
}];

5.h

[PubNubKeyUpdate subscribeToChannelWithUpdates:self
   onChannel:@"Ajan"
       forKeys:[[NSArray alloc] initWithObjects:
          @"balanceLabel.text", nil]];