Too Simple StatusManager in Objective-C (CC0)

StatusManager.h

//
//  StatusManager.h
//
//  Created by kyontan on 2015/12/22.
//  Licensed under CC0
//

#import <Foundation/Foundation.h>

typedef NS_ENUM(NSInteger, Status) {
    StatusNotValid = 0,
    StatusInitial = 1,
    StatusA,
    StatusB
};

typedef NS_ENUM(NSInteger, Action) {
    ActionFoo,
    ActionBar,
    ActionNyan,
};

@interface StatusManager : NSObject

@property (assign, nonatomic, readonly) Status status;

- (instancetype)init;

- (void)addTransition:(Action)action
                 from:(NSSet *)from
                   to:(Status)to
                 with:(void (^)(id))transition;

- (Status)transit:(Action)action;

- (Status)transit:(Action)action
     withUserData:(id)userData;

@end

StatusManager.m

//
//  StatusManager.m
//
//  Created by kyontan on 2015/12/22.
//  Licensed under CC0
//

#import "StatusManager.h"

@interface StatusManager ()

// Action -> NSSet<@(Status)>
@property (strong, nonatomic) NSMutableDictionary *fromSetOfAction;

// Action -> @(Status)
@property (strong, nonatomic) NSMutableDictionary *toOfAction;

// Action -> (void (^)(void))
@property (strong, nonatomic) NSMutableDictionary *transitions;

@property (assign, nonatomic) Status status;

@end

@implementation StatusManager

- (instancetype)init {
    self = [super init];
    
    if (self) {
        _status = StatusInitial;
        _fromSetOfAction = [NSMutableDictionary dictionary];
        _toOfAction      = [NSMutableDictionary dictionary];
        _transitions     = [NSMutableDictionary dictionary];
    }
    
    return self;
}

- (void)addTransition:(Action)action
                 from:(NSSet *)from
                   to:(Status)to
                 with:(void (^)(id))transition {
    NSNumber *naction = @(action);
    
    _fromSetOfAction[naction] = from;
    _toOfAction[naction] = @(to);
    _transitions[naction] = transition;
}

- (Status)transit:(Action)action {
    return [self transit:action withUserData:nil];
}

- (Status)transit:(Action)action
                   withUserData:(id)userData {
    NSNumber *naction = @(action);
    Status old = _status, ret;
    
    
    if ([_fromSetOfAction[naction] containsObject:@(_status)]) {
        void (^action)(id) = _transitions[naction];
        action(userData);
        
        _status = [_toOfAction[naction] integerValue];
        ret = _status;
    } else {
        ret = StatusNotValid;
    }
    
    NSLog(@"Status transit: %ld - (%ld) -> %ld ", (long)old, (long)action, (long)ret);
    return ret;
}

ViewController.h

@interface ViewController : UIViewController

@property (nonatomic, strong) StatusManager *status_manager;

@end

ViewController.m

@implementation ViewController
- (void)viewDidLoad {
    _status_manager = [StatusManager new];
    __weak __block typeof(self) weakSelf = self;
    
    [_status_manager addTransition:ActionFoo
                              from:[NSSet setWithArray:@[@(StatusInitial), @(StatusA)]]
                                to:StatusB
                              with:^(id userdata) {
                                  [weakSelf displayEverything];
                              }];
    
    [_status_manager addTransition:ActionBar
                              from:[NSSet setWithArray:@[@(StatusB)]]
                                to:StatusA
                              with:^(id userdata) {
                                  // do something
                              }];

    [_status_manager addTransition:ActionNyan
                              from:[NSSet setWithArray:@[@(StatusA), @(StatusB)]]
                                to:StatusB
                              with:^(id userdata) {
                                  // do something
                              }];
}
@end

- (IBAction)pushSomeButton:(id)sender {
    [_status_manager transit:ActionFoo];
}