Weird error with NSJSONSerialization and UIPIckerView - ios

Question

The way I have my program working is it pulls data down into the program via AFHTTPClient. Then I get my response data. I then take this data and parse it into a NSMutableArray via NSJSONSerialization. This array is used to populate a UIPickerView.
This method fires when the user opens the app or presses a refresh button. The problem is when the app opened, the call is made and I get the data back. If I go to the picker it seems empty but when you scroll down the bottom 2 of 5 are in there and when you scroll back up the others get in too. If at any point I press the refresh button the errors go away and the picker is properly populated. Any reason why it is not working properly? I reloadAllComponents after each call is made too.
-(void) getData{
// Paramaters
NSString *lat = #"40.435615";
NSString *lng = #"-79.987872";
NSDictionary *params = [NSDictionary dictionaryWithObjectsAndKeys: lat, #"lat", lng, #"lng", nil];
// posting the data and getting the response
AFHTTPClient *client = [[AFHTTPClient alloc] initWithBaseURL:[NSURL URLWithString:#"http://mysite.com/"]];
[client postPath:#"/mypostpath.php" parameters:params success:^(AFHTTPRequestOperation *operation, id responseObject) {
NSString *text = [[NSString alloc] initWithData:responseObject encoding:NSUTF8StringEncoding];
NSLog(#"Response: %#", text);
NSError *error;
json = [NSJSONSerialization JSONObjectWithData:responseObject options:kNilOptions error:&error];
// setting the first location to the text feild
NSDictionary* name = [json objectAtIndex:0];
locationField.text = [name objectForKey:#"name"];
} failure:^(AFHTTPRequestOperation *operation, NSError *error) {
NSLog(#"%#", [error localizedDescription]);
}];
// reload the picker
[pickerCust reloadAllComponents];
// setting the first location to the text feild
NSDictionary* name = [json objectAtIndex:0];
locationField.text = [name objectForKey:#"name"];
}

Answer 1

The problem is because the [pickerCust reloadAllComponents]; is being called before the block that loads the data is finished. Move the call into the success block.
Since it interacts with a UI component, wrap it in an dispatch_async so it runs on the main queue.
dispatch_async(dispatch_get_main_queue(), ^{
[pickerCust reloadAllComponents];
});