Creating table view controllers from data retrieved in View Did Load

Question

Hi I am pretty new to creating Table View Controllers. I'm having difficulty trying to load data retrieved via Json in the ViewDidLoad section, into a table view controller. The first thing I noticed is that the array where I eventually put my json data (dataArray) is not available in: numberOfRowsInSection, so I declared it outside viewDidLoad but now see that when I debug the array is empty when it gets to numberOfRowsInSection. I did test the retrieval code beforehand so am sure it works. I have a couple of questions: 1. why is that dataArray is empty in the other methods? 2. is it fine to load data for displaying in tableviews in ViewDidLoad or should I really be loading this data somewhere else where it is more visible and available for use by the tableview methods?

Here is the code:

NSArray *dataArray = nil;


- (void)viewDidLoad {
    [super viewDidLoad];

    dataArray = [[NSArray alloc] init];

    //  Set URL variable with Token
    NSString *token = @"99fdf505547d607e65b8b8ff16113337";
    NSString *teacherUrl = [NSString stringWithFormat: @"https://covle.com/apps/api/nextdoorteacher/teachers?t=%@",token];

    //  Set up the session configuration
    NSURLSessionConfiguration *sessionConfiguration = [NSURLSessionConfiguration defaultSessionConfiguration];
    NSURLSession *session = [NSURLSession sessionWithConfiguration:sessionConfiguration];

    [[session dataTaskWithURL:[NSURL URLWithString:teacherUrl]
            completionHandler:^(NSData *data,
                                NSURLResponse *response,
                                NSError *error) {
                NSLog(@"response ==> %@", response);

                if (!error) {
                    NSHTTPURLResponse *httpResponse = (NSHTTPURLResponse *)response;
                    if (httpResponse.statusCode == 200){

                        NSDictionary *jsonData = [NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingMutableContainers|NSJSONReadingAllowFragments error:&error];

                        NSLog(@" heres the serialised json ===> %@", jsonData);
                        // move serialised JSON into Array (as the data contained is in array)

dataArray=(NSArray*)[jsonData copy];

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {

    // Return the number of sections.
    return 1;
}

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {

    // Return the number of rows in the section.
    return dataArray.count;
    NSLog(@"Array count is set to ===> %@", dataArray.count);

Any help to understand and fix this would be very much appreciated. Thanks

Answer 1

For this NSArray *dataArray=(NSArray*)[jsonData copy]; You are creating a new local variable named dataArray which is NOT the same as the global dataArray which u allocated in viewDidLoad, so just write this dataArray = (NSArray*)[jsonData copy]; and you will get the array count as expected in numberOfRowsInSection

EDIT: call [self.tableview reloadData] after dataArray = (NSArray*)[jsonData copy] for calling tableview delegate methods to fire once again!