Deferred

Simple, straightforward, promise library written in Swift.

A promise represents the eventual value or error that is provided by an asynchronous function.

Basic usage

To interact with a promise's eventual value or error, we give the promise a new callback by calling then with a fulfilled block and a rejected block.

In this example, assume fetchName is some function that returns a promise. The promise will be either fulfilled with a name (String) if the async operation completes, or rejected with an error (NSError) if async operation fails.

fetchName.then({ (name: String) in
  // fetched name successfully
  println("Hello, \(name)!")
}, { (error: NSError) in
  // failed to fetch name
  println(error)
})