Directional gesture recognizer

MMDirectionPanGestureRecognizer.h

//
//  MMDirectionPanGestureRecognizer.h
//  MMSimplifiedTransitions
//
//  Created by Igor Muzyka on 8/3/14.
//  Copyright (c) 2014 Igor Muzyka. All rights reserved.
//

#import <UIKit/UIKit.h>

typedef enum {
    MMDirectionPanGestureRecognizerDirectionNone,
    MMDirectionPanGestureRecognizerDirectionUp,
    MMDirectionPanGestureRecognizerDirectionDown,
    MMDirectionPanGestureRecognizerDirectionLeft,
    MMDirectionPanGestureRecognizerDirectionRight
} MMDirectionPanGestureRecognizerDirection;

@interface MMDirectionPanGestureRecognizer : UIPanGestureRecognizer

+ (instancetype)setupInViewController:(UIViewController *)viewController;

@end

MMDirectionPanGestureRecognizer.m

//
//  MMDirectionPanGestureRecognizer.m
//  MMSimplifiedTransitions
//
//  Created by Igor Muzyka on 8/3/14.
//  Copyright (c) 2014 Igor Muzyka. All rights reserved.
//

#import "MMDirectionPanGestureRecognizer.h"

@interface MMDirectionPanGestureRecognizer ()

@property (nonatomic, assign) MMDirectionPanGestureRecognizerDirection direction;
@property (nonatomic, strong) UIViewController *containingViewController;

@end

@implementation MMDirectionPanGestureRecognizer

- (id)initWithTarget:(UIViewController *)target action:(SEL)action {
    self = [super initWithTarget:self action:action];
    
    if (self) {
        self.containingViewController = target;
    }
    
    return self;
}

+ (instancetype)setupInViewController:(UIViewController *)viewController {
    MMDirectionPanGestureRecognizer *recognizer = [[self alloc] initWithTarget:viewController action:@selector(handleDirectionalPanGestureRecognizer:)];
    
    [viewController.view addGestureRecognizer:recognizer];
    
    return recognizer;
}

- (void)handleDirectionalPanGestureRecognizer:(MMDirectionPanGestureRecognizer *)recognizer {
    switch (recognizer.state) {
        case UIGestureRecognizerStateBegan:
            [self didBeganGesture];
            break;
        case UIGestureRecognizerStateEnded:
            [self didEndGesture];
            break;
        case UIGestureRecognizerStateCancelled:
            [self didCancelledGesture];
            break;
        case UIGestureRecognizerStateChanged:
            [self stateChanged];
            break;
        default:
            break;
    }
}

#pragma mark - Life Cycle

- (void)didBeganGesture {
    [self updateDirectionForCurrentState];
}

- (void)didEndGesture {
    [self updateDirectionForCurrentState];
}

- (void)stateChanged {
    
}

- (void)didCancelledGesture {
    
}

#pragma mark - Helper methods

- (void)updateDirectionForCurrentState {
    if (self.state == UIGestureRecognizerStateBegan) {
        CGPoint velocity = [self velocityInView:self.containingViewController.view];
        
        if (abs(velocity.x) > abs(velocity.y)) {
            if (velocity.x > 0) {
                self.direction = MMDirectionPanGestureRecognizerDirectionRight;
            } else {
                self.direction = MMDirectionPanGestureRecognizerDirectionLeft;
            }
        } else {
            if (velocity.y > 0) {
                self.direction = MMDirectionPanGestureRecognizerDirectionDown;
            } else {
                self.direction = MMDirectionPanGestureRecognizerDirectionUp;
            }
        }
    } else if (self.state == UIGestureRecognizerStateCancelled || self.state == UIGestureRecognizerStateEnded || self.state == UIGestureRecognizerStateFailed){
        self.direction = MMDirectionPanGestureRecognizerDirectionNone;
    }
}

@end