Objective-C Singleton

DataStore.h

#import <Foundation/Foundation.h>

@interface DataStore : NSObject

+ (instancetype)sharedManager;

@end

DataStore.m

#import "DataStore.h"

@implementation DataStore

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

@end