iOS - Parse - PFQuery Not Working

Question

I am creating a custom class ChatRequest, but when I try to query it, it will not return any custom keys.

Here is my code:

- (void)viewDidAppear:(BOOL)animated
{
    [super viewDidAppear:animated];
    PFQuery *query = [PFQuery queryWithClassName:@"ChatRequest"];
    [query setValue:[PFUser currentUser].username forKey:@"toUser"];
    NSArray *objects = [query findObjects];
    for (NSUInteger i = 0; i < objects.count; i++) {
        PFObject *object = [objects objectAtIndex:i];
        UIAlertView *alertView = [[UIAlertView alloc] initWithTitle:@"Chat Request!" message:object.sendingUser + @"wants to chat with you!" delegate:self cancelButtonTitle:@"Decline" otherButtonTitles:@"Accept", nil];
        [alertView show];
    }
}

Can anyone help? I checked that my class was correct and the keys were there, but it still won't work.

Answer 1

You don't use setValue to add a constraint to a query. You use whereKey:equalTo:, so your code should be:

- (void)viewDidAppear:(BOOL)animated
{
    [super viewDidAppear:animated];
    PFQuery *query = [PFQuery queryWithClassName:@"ChatRequest"];
    [query whereKey:@"toUser" equalTo:[PFUser currentUser].username ];
    NSArray *objects = [query findObjects];
    for (NSUInteger i = 0; i < objects.count; i++) {
        PFObject *object = [objects objectAtIndex:i];
        UIAlertView *alertView = [[UIAlertView alloc] initWithTitle:@"Chat Request!" message:object.sendingUser + @"wants to chat with you!" delegate:self cancelButtonTitle:@"Decline" otherButtonTitles:@"Accept", nil];
        [alertView show];
    }
}

However, for performance reasons it is a bad idea to call the find objects synchronously like this. You should use - (void)findObjectsInBackgroundWithBlock:(PFArrayResultBlock)block to allow the query to complete in the background. In the completion block you can refresh your UI.

Also, from a design point of view your toUser should be a reference type column, not a string type. You could then use

[query whereKey:@"toUser" equalTo:[PFUser currentUser]];