iOS Networking API Design Pattern Ideas?

I have the following design pattern query problem. I have a web service in PHP from which I want to perform, log in authorisation, and SQL operations, some with NSDictionary responses, and some with BOOL responses.

I have had a search for design patterns and hit this: Best architectural approaches for building iOS networking applications (REST clients)

Now although this post is very interesting, I don't think I need anything as complicated. I have started with a singleton object as a assetDBConnection, but I don't know whether this is the best idea.

The only way I can think of having my assetDBConnection abstracted away from my APIWebRetrieve data retriever is to pull out and compare strings from the response. See below:

-(void)APIWebRetrieveFinished:(APIWebRetrieve *)api
{
    NSLog(@"api:%@",[api description]);
    NSLog(@"%@",api.dataString);
    NSError *error;
    if (api.dataString) {
        NSDictionary *results=[NSJSONSerialization JSONObjectWithData:[api.dataString dataUsingEncoding:NSStringEncodingConversionAllowLossy]
                                    options:NSJSONReadingMutableContainers
                                      error:&error];
        [self.delegate assetDBresult:results];
        if ([[results objectForKey:@"type"] isEqualToString:@""]){
            //Check for string key here
       }
    }
}

Any help appreciated.