At Build 2018, Microsoft will announce that customers will now be able to access their Windows 10 Timeline on an iPhone with Microsoft Edge.
Your Microsoft Edge browsing sessions on an iPhone or iPad are included in the Timeline experience on a Windows 10 PC already. So, while you're working on your Windows 10 device, you'd be able to navigate to your past browsing sessions from your iPhone or iPad.
The new Timeline feature introduces a new way to resume past activities you started on the PC you’re using, other Windows PCs that you work on as well as your iOS and Android devices. Essentially, Timeline enhances the traditional Task View feature allowing you to switch between currently running apps and past activities. With the latest Windows 10 April 2018 Update, Cortana too is Timeline-aware.
Microsoft also announced that Microsoft Launcher app on Android will support Timeline for cross-device app launching. So essentially, Timeline will now be available across the board - on iOS, Timeline will be built into Microsoft Edge while on Android, it will be integrated with the Microsoft Launcher.
While it's relatively easier to integrate services on Android, especially since Microsoft has its own launcher, looks like Microsoft Edge is the only playground Microsoft will get on iOS which is a tighter platform. We'll learn more about it on Day 2 keynote of Build 2018, so stay tuned for more information.