Add AsyncGroup struct to handle execution of groups of multiple dispatch blocks.

[eneko]

AsyncGroup

AsyncGroup facilitates working with groups of asynchronous blocks.

Multiple dispatch blocks with GCD:

let group = AsyncGroup()
group.background {
    // Run on background queue
}
group.utility {
    // Run on utility queue, in parallel to the previous block
}
group.wait()

All modern queue classes:

group.main {}
group.userInteractive {}
group.userInitiated {}
group.utility {}
group.background {}

Custom queues:

let customQueue = dispatch_queue_create("Label", DISPATCH_QUEUE_CONCURRENT)
group.customQueue(customQueue) {}

Wait for group to finish:

let group = AsyncGroup()
group.background {
    // Do stuff
}
group.background {
    // Do other stuff in parallel
}
// Wait for both to finish
group.wait()
// Do rest of stuff

Custom asynchronous operations:

let group = AsyncGroup()
group.enter()
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0)) {
    // Do stuff
    group.leave()
}
group.enter()
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0)) {
    // Do other stuff in parallel
    group.leave()
}
// Wait for both to finish
group.wait()
// Do rest of stuff

[duemunk]

Looks really great :100:

Sorry for not looking at it sooner :/

[100mango]

@eneko @duemunk Would it be better if it support notify?

simply add

  public func notify(queue: dispatch_queue_t = GCD.mainQueue(), block: dispatch_block_t){
        dispatch_group_notify(group, queue, block)
    }

turn

dispatch_group_t group = dispatch_group_create();

dispatch_group_enter(group);
// do something async
{
 dispatch_group_leave(group);
}

dispatch_group_enter(group);
//do something async
{
        dispatch_group_leave(group);
}

dispatch_group_notify(group, dispatch_get_main_queue()) {
};

into this

let group = AsyncGroup()
group.background {
    // Run on background queue
}
group.utility {
    // Run on utility queue, in parallel to the previous block
}
group.notify{
//Run on main queue
}

82

[eneko]

I like it. It will be a great non-blocking alternative to group.wait.

[100mango]

Thanks, eneko. I will try my best to enhance the documentation.