Parse SDK with iOS Device: Can't Load Data from Query onto UITableView

Question

When I run the following code, nothing appears on my UITableView . I created a global NSMutableArray for storing the results of a query on Parse, but I can't manage to use that array to load the cells on the UITableView .

Thanks!

#import "ViewController.h"
#import "MenuViewController.h"
#import "Parse/Parse.h"

@interface ViewController ()

@end

@implementation ViewController {
    CLLocationManager *locationManager;
}

@synthesize eventTableView;
@synthesize eventTableViewCell;

- (void)viewDidLoad
{
    [super viewDidLoad];
    [self loadEvents];
}

- (void) loadEvents
{
    eventNames = [[NSMutableArray alloc] init];

    PFQuery *event_query = [PFQuery queryWithClassName:@"Event"];
    [event_query findObjectsInBackgroundWithBlock:^(NSArray *objects, NSError *error) {
    if (!error) {
        NSLog(@"Successfully retrieved %lu scores.", (unsigned long)objects.count);
        for (PFObject *object in objects) {
            [eventNames addObject:[object objectForKey:@"event_name"]];
            NSLog(@"%@", [object objectForKey:@"event_name"]);
            NSLog(@"%lu", (unsigned long)eventNames.count);
        }
    } else {
        NSLog(@"Error: %@ %@", error, [error userInfo]);
    }
    }];
}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
}

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
    return 1;
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
    return [eventNames count];
}
- (UITableViewCell *)tableView:(UITableView*)tableView cellForRowAtIndexPath:(NSIndexPath     *)indexPath
{
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@"MainCell"];

    if (cell == nil) {
        cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:@"MainCell"];
    }

    NSString *cellText = [NSString stringWithFormat:@"%@",eventNames[indexPath.row]];
    NSLog(@"%@", eventNames[indexPath.row]);

    cell.textLabel.text = cellText;

    return cell;
}

@end

Answer 1

Copy and paste the following loadEvents method

- (void) loadEvents
{
eventNames = [[NSMutableArray alloc] init];

PFQuery *event_query = [PFQuery queryWithClassName:@"Event"];
[event_query findObjectsInBackgroundWithBlock:^(NSArray *objects, NSError *error) {
if (!error) {
    NSLog(@"Successfully retrieved %lu scores.", (unsigned long)objects.count);
    for (PFObject *object in objects) {
        [eventNames addObject:[object objectForKey:@"event_name"]];
        NSLog(@"%@", [object objectForKey:@"event_name"]);
        NSLog(@"%lu", (unsigned long)eventNames.count);
    }
    [eventTableView reloadData];
} else {
    NSLog(@"Error: %@ %@", error, [error userInfo]);
}
}];

}

Every time you asynchronously fetch data for table view, you have to reload the whole table or the changed sections.

Answer 2

I'm guessing that the result from findObjectsInBackground returned after the tableview has already displayed. Did the NSLog print out the results that you expected?

One thing to try is to add a

[eventTableView reloadData];

after the for loop , which will tell the tableview to reload the data again.