Objective-C Singleton Pattern

MySingeltonClass.h

#import <Foundation/Foundation.h>

@interface MySingeltonClass : NSObject

+ (instancetype)sharedInstance;

@end

MySingeltonClass.m

#import "MySingeltonClass.h"

static MySingeltonClass *_sharedInstance = nil;

@implementation MySingeltonClass

+ (instancetype)sharedInstance {
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        _sharedInstance = [[MySingeltonClass alloc] init];
    });
    return _sharedInstance;
}

@end