async-swift

Async is a utility module which provides straight-forward, powerful functions for working with asynchronous Swift. It's heavily inspired and influenced by Caolan McMahon's Async.js.

Documentation

Collections

• each
• eachSeries

Collections

### each(arr, iterator, finished)

Applies the function iterator to each item in arr, in parallel. The iterator is called with an item from the list, and a callback for when it has finished. If the iterator passes an error to its asyncCallback, the main finished-callback (for the each function) is immediately called with the error.

Note, that since this function applies iterator to each item in parallel, there is no guarantee that the iterator functions will complete in order.

Arguments

• arr - An array to iterate over.
• iterator(item, asyncCallback) - A function to apply to each item in arr. The iterator is passed a asyncCallback(error) which must be called once it has completed. If no error has occurred, the asyncCallback should be run with a nil argument.
• finished(error) - A callback which is called when all iterator functions have finished, or an error occurs.

Examples

var posts = [17, 15, 13]

Async.each(posts, iterator: { (post, asyncCallback) -> Void in
    NewsAPI.loadPost(post) { (possibleError: String?, content: String) -> () in
        if let error = possibleError {
            asyncCallback(error: error)
        } else {
            loadedPosts[post] = content
            asyncCallback(error: nil)
        }
    }
}) { (error: String?) -> Void in
    if error != nil {
        println("An error occured: \(error!)")
    } else {
        println("All posts loaded")
    }
}

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### eachSeries(arr, iterator, finished)

The same as each, only iterator is applied to each item in arr in series. The next iterator is only called once the current one has completed. This means the iterator functions will complete in order.

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