gistfile1.m

void NSAnimationContextRunAnimationBlock( dispatch_block_t group, dispatch_block_t completionHandler, NSTimeInterval time )
{
    [NSAnimationContext runAnimationBlock:group
                        completionHandler:completionHandler
                                 duration:time];
}

+ (void)runAnimationBlock:(dispatch_block_t)group
        completionHandler:(dispatch_block_t)completionHandler
                 duration:(NSTimeInterval)time
{    
    // run animation
    
    [NSAnimationContext beginGrouping];
    [[NSAnimationContext currentContext] setDuration:time];
    group();
    [NSAnimationContext endGrouping];
    
    // block delay
    dispatch_time_t popTime = dispatch_time( DISPATCH_TIME_NOW, (double)time * NSEC_PER_SEC);
    dispatch_after( popTime, dispatch_get_main_queue(), completionHandler );
    
}