Turn page programmatically in UIPageViewController when using UIPageViewControllerDataSource?

Question

I have an UIPageViewController and a class which conforms to UIPageViewControllerDataSource and manages the UIViewControllers which UIPageViewContr

Answer 1

Old question but the following implementation calls delegate and dataSource methods for turning to previous or next page (But doesn't check if delegate or dataSource is set):

- (IBAction)navigateReverse:(id)sender
{
    UIViewController *controller = [self.dataSource pageViewController:self viewControllerBeforeViewController:self.designViewControllers[self.currentIndex]];

    if (!controller)
    {
        return;
    }

    NSArray *newViewControllers = @[controller];

    NSArray *previousViewControllers = self.viewControllers;

    __weak __typeof(self) weakSelf = self;

    [self.delegate pageViewController:self willTransitionToViewControllers:newViewControllers];
    [self setViewControllers:newViewControllers direction:UIPageViewControllerNavigationDirectionForward animated:YES completion:^(BOOL finished) {
        [weakSelf.delegate pageViewController:weakSelf didFinishAnimating:finished previousViewControllers:previousViewControllers transitionCompleted:finished];
    }];
}

- (IBAction)navigateForward:(id)sender
{
    UIViewController *controller = [self.dataSource pageViewController:self viewControllerAfterViewController:self.designViewControllers[self.currentIndex]];

    if (!controller)
    {
        return;
    }

    NSArray *newViewControllers = @[controller];

    NSArray *previousViewControllers = self.viewControllers;

    __weak __typeof(self) weakSelf = self;

    [self.delegate pageViewController:self willTransitionToViewControllers:newViewControllers];
    [self setViewControllers:newViewControllers direction:UIPageViewControllerNavigationDirectionForward animated:YES completion:^(BOOL finished) {
        [weakSelf.delegate pageViewController:weakSelf didFinishAnimating:finished previousViewControllers:previousViewControllers transitionCompleted:finished];
    }];
}