#pragma mark -数据源协议的方法
//返回前一页
-(UIViewController*)pageViewController:(UIPageViewController *)pageViewController viewControllerBeforeViewController:(UIViewController *)viewController
{
    //获取当前页
    NSInteger index = ((PageContentViewController*) viewController).pageIndex;
    if ((index == 0) || (index == NSNotFound))
    {
        return nil;
    }
    
    // 返回数据前关闭交互，确保只允许翻一页
    pageViewController.view.userInteractionEnabled = NO;
    
    //前一页
    index --;

    return [self viewControllersAtIndex:index];
    
}

//返回后一页
-(UIViewController*)pageViewController:(UIPageViewController *)pageViewController viewControllerAfterViewController:(UIViewController *)viewController
{
    //获取当前页
    NSInteger index = ((PageContentViewController*) viewController).pageIndex;
    if ((index == [self.arrayM count]-1) || (index == NSNotFound))
    {
        return nil;
    }
    
    // 返回数据前关闭交互，确保只允许翻一页
    pageViewController.view.userInteractionEnabled = NO;
    
    //后一页
    index++;
    
    return [self viewControllersAtIndex:index];
}

#pragma mark -代理的方法
-(void)pageViewController:(UIPageViewController *)pageViewController didFinishAnimating:(BOOL)finished previousViewControllers:(NSArray *)previousViewControllers transitionCompleted:(BOOL)completed
{
    if(finished && completed)
    {
        // 无论有无翻页，只要动画结束就恢复交互。
        pageViewController.view.userInteractionEnabled = YES;
    }
}

#pragma mark -返回当前页的控制器
-(PageContentViewController*)viewControllersAtIndex:(NSInteger)index
{
    if ([self.arrayM count] == 0 || index == [self.arrayM count])
    {
        return nil;
    }
    
    //创建内容控制器
    PageContentViewController *pageContentVC = [[PageContentViewController alloc]init];
    
    pageContentVC.pageTitle = [self.arrayM objectAtIndex:index];

    pageContentVC.view.backgroundColor = [UIColor grayColor];
    
    pageContentVC.pageIndex = index;
    
    return pageContentVC;
}