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, just add these lines of code 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.

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 didn'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.