As Apple and Google prepare to launch updates of their mobile operating systems in the next couple months, they're letting developers take new previews and beta releases for test runs.

Released yesterday, the Android O Developer Preview 4 (pictured above) is the final preview to come out before Google rolls out the completed version, expected sometime in September. The latest preview gives developers the chance to test apps on a near-final version to ensure they perform as intended.

Apple, meanwhile, also released an update yesterday: iOS 11 Beta 4 for developers. A new version of the public iOS 11 beta, last updated late last month, is not out yet but will likely become available soon.

Google: Test Now for Better Engagement Later

Android O, the successor to last year's Android Nougat, will come with a variety of new features that will encourage better user engagement with developers' apps, Google vice president of engineering Dave Burke said yesterday on the Android Developers Blog. Android O is also designed to improve battery life and Wi-Fi connectivity.

"Today's Developer Preview 4 system images give you an excellent way to test your current apps on the near-final version of Android O," Burke noted. "By testing now, you can make sure your app offers the experience you want as users start to upgrade to the official Android O platform."

Other new features arriving with Android O include new notifications channels to unify how users manage notifications, notification badges (called "dots") to highlight news about channels and apps, support for pinning app shortcuts and widgets onto the launcher, support for a new picture-in-picture mode, and upgraded autofill capabilities.

Devices enrolled in Google's Android beta program will be automatically updated when the full version of Android O comes out, Burke said. The latest preview is available for the Pixel, Pixel XL, Pixel C, Nexus 5X, Nexus 6P, Nexus Player, and Android Emulator.

While Google hasn't yet announced the official name for Android O, a number of signs, including the types of cookies offered at its recent I/O developers conference, point to the likelihood that it will be called Android Oreo.

Apple Updates App Store, Adds New Splash Screens

Apple, in the meantime, continues to put the finishing touches on its coming iOS update, introducing a number of changes with the iOS 11 Beta 4 that launched yesterday.

Features in the latest developer preview include new splash screens for the Notes and Photos apps, an updated icon for the Contacts app, updated storage capacity values, easier viewing of what's new in the App Store, and a new user interface for opening apps from notifications.

Apple has said iOS 11 will be the "biggest software release ever for iPad." Some of the changes expected to arrive with the new operating system include a new keyboard mode for easier one-handed typing, a "Do Not Disturb" feature for driving, new multitasking capabilities, and a smarter, more multilingual Siri intelligent digital assistant.

New versions of iOS and Apple's operating systems for Macs, Apple Watches, and Apple TV typically come out in September, ahead of the newest iPhones. While Apple might follow its typical operating system release schedule this year, it's widely expected to delay the launch of its 10th anniversary iPhone until at least October, according to multiple reports.