Question

I don’t know how to explain but… If you understand me when I say a “loading circle” perfect, I just want to do this

    // Start loading in the middle of the screen frozing all interaction
    for (int c = 0; c < ([barcos count] - 1); c++)
    {
        NSArray *datos = [[barcos objectAtIndex:c] componentsSeparatedByString:@";"];
        NSString *nombreImagen = [datos objectAtIndex:2];
        NSURL *accesoFtp = [NSURL URLWithString:[NSString stringWithFormat:@"%@/%@",urlFtp,nombreImagen]];
        NSData *imagen = [NSData dataWithContentsOfURL:accesoFtp];
        [imagen writeToFile:[[NSString alloc] initWithString: [docsDir stringByAppendingPathComponent:[NSString stringWithFormat:@"Barcos/%@",nombreImagen]]] atomically:NO];
    }
    // Stop frozing all interaction and remove the loading circle

Probabbly I have to add a thread or something but I don’t know how to do what I want exactly I hope you can help me, again. Thanks.

EDIT:

UIActivityIndicatorView *activityIndicator;
activityIndicator = [[UIActivityIndicatorView alloc]initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleGray];
activityIndicator.frame = CGRectMake(0.0, 0.0, 40.0, 40.0);
activityIndicator.center = self.view.center;
[self.view addSubview: activityIndicator];

activityIndicator.startAnimating;

dispatch_queue_t queue = dispatch_get_global_queue(0,0);

dispatch_async(queue, ^{

        for (int c = 0; c < ([barcos count] - 1); c++)
        {
            NSArray *datos = [[barcos objectAtIndex:c] componentsSeparatedByString:@";"];
            NSString *nombreImagen = [datos objectAtIndex:2];
            NSURL *accesoFtp = [NSURL URLWithString:[NSString stringWithFormat:@"%@/%@",urlFtp,nombreImagen]];
            NSData *imagen = [NSData dataWithContentsOfURL:accesoFtp];
        [imagen writeToFile:[[NSString alloc] initWithString: [docsDir stringByAppendingPathComponent:[NSString stringWithFormat:@"Barcos/%@",nombreImagen]]] atomically:NO];
        }

    dispatch_sync(dispatch_get_main_queue(), ^{
        activityIndicator.stopAnimating;
    });
});

Two things

 1.- The activity indicator is too small but works, if I can to it bigger or same size but make darker the background would be better (Thanks!)
 2.- I have a warning with startAnimating and stopAnimating "Property access result unused - getters should not be used for side effects"

Thanks =)

Answer 1

It can be done using MBProgressHUD

Also check this code:

//Show your activity indicator here

dispatch_queue_t queue = dispatch_get_global_queue(0,0);

dispatch_async(queue, ^{
    for (int c = 0; c < ([barcos count] - 1); c++)
    {
        NSArray *datos = [[barcos objectAtIndex:c] componentsSeparatedByString:@";"];
        NSString *nombreImagen = [datos objectAtIndex:2];
        NSURL *accesoFtp = [NSURL URLWithString:[NSString stringWithFormat:@"%@/%@",urlFtp,nombreImagen]];
        NSData *imagen = [NSData dataWithContentsOfURL:accesoFtp];
        [imagen writeToFile:[[NSString alloc] initWithString: [docsDir stringByAppendingPathComponent:[NSString stringWithFormat:@"Barcos/%@",nombreImagen]]] atomically:NO];
    }
    dispatch_sync(dispatch_get_main_queue(), ^{
              //hide that activity indicator here
            });

});

EDIT:

Never call methods like:

activityIndicator.startAnimating;
activityIndicator.stopAnimating;

These are used for calling setters and getters.

Change it to:

[activityIndicator startAnimating];
[activityIndicator stopAnimating];