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iOS Build a Self-Destructing Message iPhone App Retrieving and Viewing Data from Parse.com Retrieving Data from Parse.com

Posted by Eduardo Mejía
Eduardo Mejía
36,816 Points

Value of type 'NSUInteger' should not be used as format arguments.

I have 2 problems. First, when I write 

NSLog(@"Retrieved %d messages", [self.messages count]);

A warning appears: "Value of type 'NSUInteger' should not be used as format arguments; add an explicit cast to 'unsigned long' instead".

The second problem is that my app crashes, this is my code:

- (void)viewWillAppear:(BOOL)animated {
    [super viewWillAppear:animated];

    PFQuery *query = [PFQuery queryWithClassName:@"Messages"];

    [query whereKey:@"recipientIds" equalTo:[[PFUser currentUser] objectId]];
    [query orderByDescending:@"createdAt"];
    [query findObjectsInBackgroundWithBlock:^(NSArray *objects, NSError *error){
        if (error) {
            NSLog(@"No mames hay un Error: %@ %@", error, [error userInfo]);
        } else {
            self.messages = objects;
            [self.tableView reloadData];
            NSLog(@"Retrieved %d messages",[self.messages count]);
        }
    }];
}

These are the errors: https://www.dropbox.com/s/uxh5oyf0d0uc8jp/Ribbit.tiff?dl=0 https://www.dropbox.com/s/npmin6291facxek/Ribbit2.tiff?dl=0

And this is my class Messages: https://www.dropbox.com/s/oc0jbdap3ey4mq1/Parse.tiff?dl=0

Please I need help. I don't know what I'm doing wrong.

Eduardo Mejía
Eduardo Mejía
36,816 Points

I found the solution, for the first problem Xcode suggested this:

NSLog(@"Retrieved %lu messages",(unsigned long)[self.messages count]);

For the second problem I was reading the documentation and changed my code to this:

- (void)viewWillAppear:(BOOL)animated {
    [super viewWillAppear:animated];
NSPredicate *predicate = [NSPredicate predicateWithFormat:@"%@ IN recipientIds", [[PFUser currentUser] objectId]];
    PFQuery *query = [PFQuery queryWithClassName:@"Messages" predicate:predicate];

    [query orderByDescending:@"createdAt"];
    [query findObjectsInBackgroundWithBlock:^(NSArray *objects, NSError *error){
        if (error) {
            NSLog(@"Error: %@ %@", error, [error userInfo]);
        } else {
            self.messages = objects;
            [self.tableView reloadData];
            NSLog(@"Retrieved %lu messages",(unsigned long)[self.messages count]);
        }
    }];
}

But... Why does the Ben's code work? I need an explanation. My English isn't that good, so I'm going to write in Spanish. En la documentación aparecen dos ejemplos de como buscar un elemento en un array:

// Find objects where the array in arrayKey contains 2.
// Using PFQuery
[query whereKey:@"arrayKey" equalTo:@2];

// Or using NSPredicate
NSPredicate *predicate = [NSPredicate predicateWithFormat:@"2 IN arrayKey"];
PFQuery *query = [PFQuery queryWithClassName:@"MyClass" predicate:predicate];

¿Por qué el primero le funciona a Ben pero a mi no, hace que la app tenga todos los errores que he mostrado anteriormente? ¿Por qué el segundo si me funciona si son dos formas distintas de hacer lo mismo?

1 Answer

landonferrier
landonferrier
25,097 Points

Eduardo, here is a full template for the social network application: Click Here.