Swift Singleton

[v5tech]

http://www.synappse.pl/swift-first-steps-singleton/

//
//  Singleton.swift
//  Test
//
//  Created by Sebastian Suchanowski on 6/5/14.
//  Copyright (c) 2014 Synappse. All rights reserved.
//

import Foundation

class Singleton {

    class func sharedInstance() -> Singleton! {
        struct Static {
            static var instance: Singleton? = nil
            static var onceToken: dispatch_once_t = 0
        }

        dispatch_once(&Static.onceToken) {
            Static.instance = self()
        }

        return Static.instance!
    }

    @required init() {

    }

}

[v5tech]

//
//  TestTests.swift
//  TestTests
//
//  Created by Sebastian Suchanowski on 6/5/14.
//  Copyright (c) 2014 Synappse. All rights reserved.
//

import XCTest

class TestTests: XCTestCase {

    override func setUp() {
        super.setUp()
    }

    override func tearDown() {
        super.tearDown()
    }

    // Helpers
    func createUniqueInstance() -> Singleton {
        return Singleton();
    }

    func getSharedInstance() -> Singleton {
        return Singleton.sharedInstance()
    }

    // Tests
    func testSingletonSharedInstanceCreated() {
        XCTAssertNotNil(getSharedInstance())
    }

    func testSingletonUniqueInstanceCreated() {
        XCTAssertNotNil(createUniqueInstance())
    }

    func testSingletonReturnsSameSharedInstances() {
        var s1 = getSharedInstance()
        var s2 = getSharedInstance()
        XCTAssertEqualObjects(s1, s2)
    }

    func testSingletonSharedInstanceSameAsUniqueInstance() {
        var s1 = getSharedInstance()
        var s2 = createUniqueInstance()
        XCTAssertNotEqualObjects(s1, s2)
    }

    func testSingletonReturnsSameUniqueInstances() {
        var s1 = createUniqueInstance()
        var s2 = createUniqueInstance()
        XCTAssertNotEqualObjects(s1, s2)
    }

}