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iOS

Posted by Mike Lee
Mike Lee
6,579 Points

FindObjectsInBackgroundWithBlock Help??

Can someone please tell me what i am doing wrong, and why I keep getting a (null) outside of the block??

Heres my code:
.m

  • (void)viewDidLoad { [super viewDidLoad];

    PFQuery *query = [PFUser query];
[query whereKey:@"selectedGym" equalTo:gymLabelText];

    [query findObjectsInBackgroundWithBlock:^(NSArray *objects, NSError *error)

     {

     self.gymRoster=objects;

 }];

    NSLog(@"%@",gymRoster);

Mike Lee
Mike Lee
6,579 Points

Not to mention but I also set it up the same way as the EditFriendsViewController as in the treehouse project and I still got a null.

1 Answer

nicktroccoli
nicktroccoli
3,765 Points
nicktroccoli
nicktroccoli
3,765 Points 
- (void)viewDidLoad {
    [super viewDidLoad];

    PFQuery *query = [PFUser query];
    [query whereKey:@"selectedGym" equalTo:gymLabelText];
    [query findObjectsInBackgroundWithBlock:^(NSArray *objects, NSError *error) {
        self.gymRoster=objects;
    }];

    NSLog(@"%@",gymRoster);
}

If your code is like the code above (just wanted to copy and paste to confirm the formatting) then your issue has to do with the query running in the background. When you call findObjectsInBackgroundWithBlock, you're telling Parse to run the given query, and execute the block that you pass in once the query finishers. In this case, you're telling Parse to go execute this query, and when it's done set your gymRoster instance variable to be the result. The reason your NSLog is always nil is because the NSLog is executing before the query finishes. Remember that you should put all code you want to be executed when the query finishes inside the block you pass in. You can't assume that the query will finish by the time you get to the NSLog since the query is executing in the background!