/*

 Copyright (C) 2015 Apple Inc. All Rights Reserved.

 See LICENSE.txt for this sample’s licensing information

 Abstract:

 The data model controller that manages our view controller pages.

 */

#import "ModelController.h"

#import "DataViewController.h"

@interface ModelController ()

@property (nonatomic, strong) NSMutableArray *pageData;

@end

#pragma mark -

@implementation ModelController

- (instancetype)init

{

    self = [super init];

    if (self != nil)

    {

        // Create the data model.

        _pageData = [NSMutableArray array];

        [self.pageData addObjectsFromArray:@[@"bunny1", @"bunny2", @"bunny3", @"bunny4"]];

    }

    return self;

}

- (DataViewController *)viewControllerAtIndex:(NSUInteger)index storyboard:(UIStoryboard *)storyboard

{

    // Return the data view controller for the given index.

    if ((self.pageData.count == 0) || (index >= self.pageData.count))

    {

        return nil;

    }

    // Create a new view controller and pass suitable data.

    DataViewController *dataViewController = [storyboard instantiateViewControllerWithIdentifier:@"DataViewController"];

    dataViewController.dataObject = self.pageData[index];

    return dataViewController;

}

- (NSUInteger)indexOfViewController:(DataViewController *)viewController

{

    // Return the index of the given data view controller.

    // For simplicity, this implementation uses a static array of model objects and the

    // view controller stores the model object; you can therefore use the model object to identify the index.

    //

    return [self.pageData indexOfObject:viewController.dataObject];

}

#pragma mark - UIPageViewControllerDataSource

- (UIViewController *)pageViewController:(UIPageViewController *)pageViewController viewControllerBeforeViewController:(UIViewController *)viewController

{

    NSUInteger index = [self indexOfViewController:(DataViewController *)viewController];

    if ((index == 0) || (index == NSNotFound))

    {

        return nil;

    }

    index--;

    return [self viewControllerAtIndex:index storyboard:viewController.storyboard];

}

- (UIViewController *)pageViewController:(UIPageViewController *)pageViewController viewControllerAfterViewController:(UIViewController *)viewController

{

    NSUInteger index = [self indexOfViewController:(DataViewController *)viewController];

    if (index == NSNotFound)

    {

        return nil;

    }

    index++;

    if (index == self.pageData.count)

    {

        return nil;

    }

    return [self viewControllerAtIndex:index storyboard:viewController.storyboard];

}

@end