NSOperation queue very basic example

gistfile1.m

// MyOperation.h
@interface MyOperation : NSOperation
@end

// MyOperation.m
@implementation MyOperation

- (void)main {
    if ([self isCancelled]) {
        NSLog(@"** operation cancelled **");
    }
    
    [self performSelectorOnMainThread:@selector(updateUserInterface) withObject:nil waitUntilDone:NO];
}

- (void)updateUserInterface {
    some UI code
}
@end