[Objective-C] Singleton Design Pattern

Signleton

// Singleton.h

#import <Foundation/Foundation.h>

@interface Singleton : NSObject

+ (Singleton *)sharedInstance;

@end

// Singleton.m

#import "Singleton.h"

@implementation Singleton

+ (Singleton *)sharedInstance
{
    static id sharedInstance;
    static dispatch_once_t oncePredicate;

    dispatch_once(&oncePredicate, ^{
        sharedInstance = [[Singleton alloc] init];
    });
    
    return sharedInstance;
}

@end