Why run Selector: withObject: afterDelay works even if the application is in the background?

Question

I do not use any special background mode. I created this simple project:

@implementation ViewController

- (void)viewDidLoad
{
    [super viewDidLoad];
    [self performSelector:@selector(callservice) withObject:nil afterDelay:5];
}

-(void) callservice
{
    NSURLRequest * urlRequest = [NSURLRequest requestWithURL:[NSURL URLWithString:@"http://google.com"]];
    NSURLResponse * response = nil;
    NSError * error = nil;
    NSData * data = [NSURLConnection sendSynchronousRequest:urlRequest
                                          returningResponse:&response
                                                      error:&error];
    if (error == nil)
    {
        // Parse data here
    }
    [self performSelector:@selector(callservice) withObject:nil afterDelay:5];
}

@end

"", . Charles , , - "www.google.com" 5 . ( , callervice performselector:withobject:afterdelay, , , - ). 10 , , , "Home" , Xcode. Xcode . . ? performselector:withobject:afterdelay 5 ? iOS ""? !