Swift Utitilies

Future.swift

//
//  Future.swift
//
//  Experimental simple Future/Promise class in Swift 2 (Beta)
//
//  NEXT: probably want to split the promise (done/fail) from the future part (the resolve/reject)
//
//  Jeremy Chone 2015-06-21

import Foundation

public class Future<T> {
	
	private var doneFunctions: [T -> Void] = []
	
	private var doneOnMainFunctions: [T -> Void] = []
	
	private var failFunctions: [ErrorType -> ()] = []
	
	private var val:T?
	
	public init(){
	}
	
	// MARK: Promise interface
	
	public func done(success: (T -> Void)) -> Future<T>{
		
		doneFunctions.append(success)
		
		return self
	}
	
	public func doneOnMain(success: (T -> Void)) -> Future<T>{
		
		doneOnMainFunctions.append(success)
		
		return self
	}
	
	public func fail(fail: (ErrorType -> ())) -> Future<T>{
		
		failFunctions.append(fail)
		
		return self
	}
	
	
	// MARK: Future interface
	
	public func resolve(result: T) -> Future<T>{
		val = result
		
		for fun in doneFunctions {
			fun(result)
		}
		
		for fun in doneOnMainFunctions {
			dispatch_async(dispatch_get_main_queue(),{
				fun(result)
			})
		}
		
		return self
	}
	
	public func reject(error: ErrorType) -> Future<T>{
		
		for fun in failFunctions{
			fun(error)
		}
		
		return self
	}
	
}

Updated for Swift 2 (beta). (Error Type)