Singleton

Singleton.swift

import Foundation

class Singleton {
    class var sharedInstance: Singleton {
        struct Static {
            static var onceToken: dispatch_once_t = 0
            static var instance: Singleton? = nil
        }
        dispatch_once(&Static.onceToken) {
            Static.instance = Singleton()
            print("Singleton")
        }
        return Static.instance!
    }
}

SingletonManager.m

@implementation SingletonManager

+ (id)sharedManager {
    static SomeManager *staticManager = nil;
    static dispatch_once_t onceToken;

    dispatch_once(&onceToken, ^{
        staticManager = [[self alloc] init];
        print("Singleton");
    });
    return staticManager;
}

@end