CODEWITHSUNDEEP
iosobjective-cjsonnsoperation
Dracknes
Dracknes

Reputation: 79

How can i reload the table after download json

I have a problem when reloading the table after downloading the data in JSON format.

Use the NSOperation to download data async.

The code that i use it's this

- (void)viewDidLoad
{
    [super viewDidLoad];

    [self loadInformactionToSql];
}
-(void)loadInformactionToSql {
    NSOperationQueue * queue = [NSOperationQueue new];
    NSInvocationOperation * operation = [[NSInvocationOperation alloc] initWithTarget:self selector:@selector(downloadJSONBDD) object:nil];
    [queue addOperation:operation];
}

-(void)downloadJSONBDD {
    NSURL * url = [NSURL URLWithString:@"http://judokatium.com/index.php/api/Belts/getBeltsWithTechnicals"];
    //Leer el JSON

    NSData * allCinturonesTecnicasJson =
    [[NSData alloc] initWithContentsOfURL:url];

    NSError *error;

    NSArray * allCinturonesJson =
    [NSJSONSerialization JSONObjectWithData:allCinturonesTecnicasJson options:kNilOptions error:&error];

    if(error) {
        NSLog(@"%@, %@", [error localizedDescription], [error localizedFailureReason]);
    } else {
        NSDictionary * cintns;
        cinturones = [[NSMutableArray alloc] init];
        for(int i = 0; i < [allCinturonesJson count]; i++){
            JLMCinturon * cinturon = [[JLMCinturon alloc] init];

            cintns = [allCinturonesJson objectAtIndex:i];

            cinturon.idCinturon = [cintns objectForKey:@"id"];

            [cinturones addObject:cinturon];


        }
        [self.tablaCinturones reloadData];
        self.tablaCinturones.hidden = NO;
    }
}

The downloaded data are correct, but not shown in the table.

How can i fix it?

Thanks and Sorry for my bad english.

Upvotes: 0

Views: 73

Answers (1)

Chris Loonam
Chris Loonam

Reputation: 5745

Put these lines

[self.tablaCinturones reloadData];
self.tablaCinturones.hidden = NO;

into a dispatch block that moves them to the main thread

dispatch_async(dispatch_get_main_queue(), ^{
    [self.tablaCinturones reloadData];
    self.tablaCinturones.hidden = NO;
});

The problem is that NSOperation moves your method calls to a different thread, and the UI cannot be updated in iOS from any thread but the main one.

Or, you could use NSOperation as you already have and as @JulianKról pointed out.

NSOperationQueue *mainQueue = [NSOperationQueue mainQueue];
NSInvocationOperation *reloadOperation = [[NSInvocationOperation alloc] initWithTarget:self.tablaCinturones selector:@selector(reloadData) object:nil];
NSInvocationOperation *hiddenOperation = [[NSInvocationOperation alloc] initWithTarget:self.tablaCinturones selector:@selector(setHidden:) object:@(NO)];
[mainQueue addOperation:reloadOperation];
[mainQueue addOperation:hiddenOperation];

Upvotes: 3

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