App Singleton

AppSingleton.h

#import <Foundation/Foundation.h>

@interface AppSingleton : NSObject

+ (AppSingleton *)sharedInstance;

@end

AppSingleton.m

#import "AppSingleton.h"

@implementation AppSingleton

+ (AppSingleton *)sharedInstance {
    static AppSingleton *sharedInstance = nil;
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        sharedInstance = [[self alloc] init];
    });
    return sharedInstance;
}

@end