@interface PersonTableViewController : UITableViewController <AddPerson> {
	NSOperationQueue *queue;
}
@end

@implementation PersonTableViewController

- (void)addPerson:(NSString *)username {
	NSInvocationOperation *operation = [[NSInvocationOperation alloc] initWithTarget:self selector:@selector(addPersonInBackground:) object:username];
	[queue addOperation:operation]; 
	[operation release];
}
@end

How to use NSOperationQueue

Objective C