[Objective-C] Unregistering block-based NotificationCenter observers using "Resource acquisition is initialization" (RAII)

NotificationToken.h

//
//  NotificationToken.h
//
//  Created by brackendev
//  Based on Ole Begemann's article and Swift implementation <https://oleb.net/blog/2018/01/notificationcenter-removeobserver/>
//

@import Foundation;

@interface NotificationToken : NSObject

- (instancetype)initWith:(NSNotificationCenter *)aNotificationCenter token:(id)aToken;

@end

NotificationToken.m

//
//  NotificationToken.m
//
//  Created by brackendev
//  Based on Ole Begemann's article and Swift implementation <https://oleb.net/blog/2018/01/notificationcenter-removeobserver/>
//

#import "NotificationToken.h"

@interface NotificationToken ()

@property (nonatomic, strong) NSNotificationCenter *notificationCenter;
@property (nonatomic) id token;

@end

@implementation NotificationToken

- (instancetype)initWith:(NSNotificationCenter *)aNotificationCenter token:(id)aToken {
    self = [super init];

    self.notificationCenter = aNotificationCenter;
    self.token = aToken;

    return self;
}

- (void)dealloc {
    [self.notificationCenter removeObserver:self.token];
}

@end

NSNotificationCenter+Token.h

//
//  NSNotificationCenter+Token.h
//
//  Created by brackendev
//  Based on Ole Begemann's article and Swift implementation <https://oleb.net/blog/2018/01/notificationcenter-removeobserver/>
//

@import Foundation;

@class NotificationToken;

@interface NSNotificationCenter (Token)

- (NotificationToken *)observeForName:(NSNotificationName)name object:(id)obj queue:(NSOperationQueue *)queue usingBlock:(void (^)(NSNotification *note))block;

@end

NSNotificationCenter+Token.m

//
//  NSNotificationCenter+Token.m
//
//  Created by brackendev
//  Based on Ole Begemann's article and Swift implementation <https://oleb.net/blog/2018/01/notificationcenter-removeobserver/>
//

#import "NSNotificationCenter+Token.h"
#import "NotificationToken.h"

@implementation NSNotificationCenter (Token)

- (NotificationToken *)observeForName:(NSNotificationName)name object:(id)obj queue:(NSOperationQueue *)queue usingBlock:(void (^)(NSNotification *note))block {
    id token = [self addObserverForName:name object:obj queue:queue usingBlock:block];

    return [[NotificationToken alloc] initWith:self token:token];
}

@end