YTPageController

[](https://travis-ci.org/Yeatse CC/YTPageController)

Yet another drop-in replacement of UIPageViewController, inspired by Apple's offical Music app.

What problem does YTPageController try to resolve?

YTPageController introduces a general solution to achieve a smooth transition when user scrolls between view controllers, just as what Apple did in their Music app:

To implement this effect, simply add these lines in your YTPageControllerDelegate:

- (void)pageController:(YTPageController *)pageController willTransitionToIndex:(NSInteger)index {
    [pageController.pageCoordinator animateAlongsidePagingInView:self.segmentedControl animation:^(id<YTPageTransitionContext>  _Nonnull context) {
        // Update your segmented control according to the information contained in YTPageTransitionContext
        self.segmentedControl.selectedSegmentIndex = [context toIndex];
    } completion:^(id<YTPageTransitionContext>  _Nonnull context) {
        if ([context isCanceled]) {
            // Revert to original state if transition canceled
            self.segmentedControl.selectedSegmentIndex = [context fromIndex];
        }
    }];
}

The key idea to control the percent of its animation is to set the CALayer's speed property to 0, and then update the timeOffset value according to UIScrollView's contentOffset. In addition to UISegmentedControl, you can also animate UITabBar or any UIView subclass you like:

Refer to the example project for detailed information.

Usage

• Using code

  You have two ways to set up your YTPageController in code:

  • Implement the YTPageControllerDataSource protocol and assign it to dataSource.
  • Assign an array of child view controllers to viewControllers.

  If you choose both methods at the same time, dataSource will take the priority.

  Since YTPageController is backed by UICollectionView, you need to call - reloadPages after you change your child view controllers later.

• Using storyboard

  You can also set up YTPageController in storyboard without any code, like what you have done with UITabBarController:

  

  Since Apple hasn't provide a custom relationship segue, you need to follow these steps to simulate it:

  1. Drag a custom segue from YTPageController to one of your child view controllers and change its class to YTPageControllerSegue;
  2. Name the identifier of this segue with the format YTPage_{index}, such as YTPage_0, YTPage_1, YTPage_2, ...

  YTPageController will find and perform all these segues in runtime to add the connected view controllers to its child view controllers.

Example

To run the example project, clone the repo, and run pod install from the Example directory first.

Requirements

iOS 8.0 or above. May be working from iOS 6.0, but I haven't test it.

Installation

YTPageController is available through CocoaPods. To install it, simply add the following line to your Podfile:

pod "YTPageController"

Author

Yeatse CC, [email protected]

License

YTPageController is available under the MIT license. See the LICENSE file for more info.