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iOS Build a Self-Destructing Message iPhone App Relating Users in Parse.com Displaying Our List of Friends

Jacob McLaws
Jacob McLaws
1,497 Points
Posted by Jacob McLaws
Jacob McLaws
1,497 Points

Friends not displaying on Ribbit App

There's another thread about this, but it didn't really get to the root of the problem I'm having.

Here it is: The friends list doesn't seem to respond to the friendsrelation query. I can add new friends, but they don't show up. I have followed the vid twice and still have the same issue. friendsViewController.m

#import "FriendsViewController.h"

@interface FriendsViewController ()

@end

@implementation FriendsViewController


- (void)viewDidLoad
{
    [super viewDidLoad];
    self.friendsRelation = [[PFUser currentUser] objectForKey:@"friendsRelation"];
    PFQuery *query = [self.friendsRelation query];
    [query orderByAscending:@"username"];
    [query findObjectsInBackgroundWithBlock:^(NSArray *objects, NSError *error) {
        if(error){
            NSLog(@"Error %@ %@", error, [error userInfo]);
        }
        else {
            self.friends = objects;
            [self.tableView reloadData];
        }
        }];

}


#pragma mark - Table view data source

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
    return 1;
}

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
    return [self.friends count];
}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *) indexPath
    {
        static NSString *CellIdentifier = @"Cell";
        UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier forIndexPath:indexPath];

        PFUser *user = [self.friends objectAtIndex:indexPath.row];
        cell.textLabel.text = user.username;

        return cell;
    }

////In a storyboard-based application, you will often want to do a little preparation before navigation
//- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender { // Get the new view controller using
//    [segue destinationViewController];// Pass the selected object to the new view controller.
//}

@end

Any help would be hugely appreciated.

Erion Vlada
Erion Vlada
13,496 Points

Using viewWillAppear will mean you are sending a lot more request then you need to the server. If you had a lot of users then it is not a good idea.

You should look into NSNotification, basically like a radio and receiver type system. When you add a friend, the radio would transmit, “I HAVE JUST ADDED A FRIEND” to which your FriendViewController (the receiver) would be listening in to that station which can then execute a method to update the list of your friends.

This is great because you will only be asking the server for information when you actually need it, instead of every single time the user goes from one view, then back to your Friends view.

Its not difficult to implement, here is a link to help you: http://stackoverflow.com/questions/2191594/send-and-receive-messages-through-nsnotificationcenter-in-objective-c

Hope this helps :)

3 Answers

Stone Preston
Stone Preston
42,016 Points
Stone Preston
Stone Preston
42,016 Points

the problem could be the fact that you are running the query in view did load. this only runs one time, when the view first gets loaded. So it runs when your first open the friends list, then you add some friends and navigate back to the friends list and the query does not run again so you dont see it update. try moving the query code into viewWillAppear:

-(void) viewWillAppear: (BOOL) animated 
{
    [super viewWillAppear:animated];
    self.friendsRelation = [[PFUser currentUser] objectForKey:@"friendsRelation"];
    PFQuery *query = [self.friendsRelation query];
    [query orderByAscending:@"username"];
    [query findObjectsInBackgroundWithBlock:^(NSArray *objects, NSError *error) {
        if(error){
            NSLog(@"Error %@ %@", error, [error userInfo]);
        }
        else {
            self.friends = objects;
            [self.tableView reloadData];
        }
        }];

}

if that does not work, verify that the friends are actually being added using the parse databrowser and double check that your relation is actually named "friendsRelation". you may have mistyped it or something

Jacob McLaws
Jacob McLaws
1,497 Points
Jacob McLaws
Jacob McLaws
1,497 Points

You're on fire Stone Preston. Thanks. I wonder why Ben's was set up with View Did Load..

Thorsten Herbst
Thorsten Herbst
11,935 Points
Thorsten Herbst
Thorsten Herbst
11,935 Points

You can do it also in ViewDidLoad. I think you have to... because Relation has to be loaded for the first time.