AFNetworking Data Fetching Method Not Called - objective-c

Question

I am creating an app where in the first view, the user is given the option to log-in or register. In the register view is a UITableViewCell that, when clicked, takes the user to a view containing a UITableView and a UIPickerView. The UITableView is working correctly, but the UIPickerView, which is supposed to dynamically pull the data it is supposed to display using a web call, is showing up but appears completely blank. Putting in a few NSLog statements, I noticed that the methods in the Model that pull the data using AFNetworking are never getting called. I've posted the code below for the UIPickerViewDelegate and UIPickerViewDataSource methods, as well as the method that is supposed to pull the data in the Model. Thanks in advance.
UIPickerViewDelegate
- (NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row
forComponent:(NSInteger)component {
return [[self.brain classChoicesForSignUp] objectAtIndex:row];
}
UIPickerViewDataSource
- (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView {
return 1;
}
- (NSInteger)pickerView:(UIPickerView *)pickerView
numberOfRowsInComponent:(NSInteger)component {
size_t numberOfRows = [self.brain classChoicesForSignUp].count;
NSLog(#"Number of Rows: %#", [[NSNumber numberWithFloat:numberOfRows] stringValue]);
return numberOfRows;
}
SignUpPickerBrain.m
#import "SignUpPickerBrain.h"
#import "AFJSONRequestOperation.h"
#implementation SignUpPickerBrain
#pragma mark - Picker Data
- (NSArray *)classChoicesForSignUp {
NSLog(#"Class choices method called");
// Note that in my code, the actual URL is present here.
NSURL *url = [NSURL URLWithString:#"the URL"];
NSURLRequest *request = [NSURLRequest requestWithURL:url];
AFJSONRequestOperation *operation = [AFJSONRequestOperation JSONRequestOperationWithRequest:request success:^(NSURLRequest *request, NSHTTPURLResponse *response, id JSON) {
NSLog(#"Success!");
NSLog([JSON description]);
} failure:nil];
[operation start];
[operation waitUntilFinished];
NSLog([operation responseJSON]);
return [operation responseJSON];
}
#end

Answer 1

There are a lot of anti-patterns going on in this code sample. I strongly recommend against your current approach, and consider the following points:
Do networking asynchronously, i.e. don't use [operation waitUntilFinished];. Any time you're creating a method that makes a network request, give it a block parameter that can be used as a callback once the results come in.
Store your results in an array property in the controller, or the like, and use that to drive your delegates and datasources. In your current approach, you will be doing a network request every single time a row is displayed (!). So instead, initialize to an empty array, and once the new results are set to that property, reload the data source. One asynchronous request. Easy.
Get rid of SignUpPickerBrain. Either use a proper Model, or just make the call itself in the Controller. The example iOS project has some great patterns to follow.
Use AFHTTPClient. If you're interacting with a particular webservice, it can be very useful to have an AFHTTPClient subclass to handle all of those requests.