Introduction
Everyone’s nostalgic for Nougat — the cat-collecting easter egg, the Pixel’s unlimited photo backup, the last Android before “gestures ruined everything.” But nostalgia lies. Android 9 Pie was braver than any Android release in years. It killed the three-button navigation bar that had defined Android since 2008. It baked Digital Wellbeing into the OS when critics were calling smartphone addiction a public health crisis. And it used on-device AI to manage your battery in ways Doze never could.
Android 9 Pie was officially released on August 6, 2018.
Pie was Android’s coming-of-age release. The navigation pill and gesture system — flawed and controversial in 9.0 — established the interaction model that all modern Android phones use. Adaptive Battery used machine learning to predict which apps you’d open and shut down the rest. App Actions and Slices integrated app functionality into system search and Google Assistant. And the Pixel 3, launched with Pie, cemented Google’s position as the camera king.
Pie also marked the end of Android’s public dessert naming — Google announced that Android 10 would just be “Android 10.” The alphabetical dessert tradition that started with Cupcake ended here.
Quick Facts
| Item | Value |
|---|---|
| Version | Android 9 |
| Codename | Pie |
| API Level | 28 |
| Release Date | August 6, 2018 |
| Linux Kernel | 4.14+ |
| Initial Device | Google Pixel / Pixel 2 (OTA), Pixel 3 (launch) |
| Previous Version | Android 8.0/8.1 Oreo |
| Next Version | Android 10 |
What’s New
Gesture Navigation
Android 9 introduced a new gesture navigation system centered on a single pill-shaped home button. Swipe up from the pill to see Overview (recent apps). Swipe up again to open the app drawer. Swipe right on the pill to Quick Switch between apps. A back button appeared contextually when needed.
This was Android’s first departure from the three-button navigation bar (Back, Home, Recents) since ICS introduced on-screen buttons in 2011. The gesture system was half-baked in 9.0 — the back button still appeared, Overview required two swipes, and the pill was awkward on larger screens — but it established the direction. Android 10 refined it. Android 12-12L made it smooth.
Google’s decision to go pill-first was a direct response to the iPhone X’s gesture bar. Apple had removed the home button entirely; Google was transitioning more cautiously. The result was a hybrid that pleased nobody: gesture enthusiasts wanted full swipe navigation; traditionalists wanted their three buttons back. Both camps were dissatisfied with Pie’s compromise.
Digital Wellbeing
Pie introduced Digital Wellbeing, Google’s response to growing concern about smartphone addiction. The feature set included:
- Dashboard: A timeline showing how much time was spent in each app, how many times the phone was unlocked, and how many notifications were received
- App Timers: Set daily time limits for specific apps; the app icon grays out when the limit is reached
- Wind Down: Schedule the screen to fade to grayscale and Do Not Disturb to activate at bedtime
- Do Not Disturb refinements: Flipping the phone face-down automatically enabled DND (Shush mode)
Digital Wellbeing was genuinely useful for self-monitoring and surprisingly non-judgmental. It presented data without moralizing, letting users decide what to do with it. Apple introduced Screen Time in iOS 12 the same year, acknowledging that the company that built the most addictive devices on earth also had a responsibility to help people use them less.
Adaptive Battery
Adaptive Battery used on-device machine learning (via DeepMind technology) to predict which apps you’d open in the near future and prioritize battery for those apps. Apps you rarely used had their background activity aggressively restricted. Apps you used frequently were kept ready.
Google claimed Adaptive Battery reduced CPU wake-ups by 30% compared to Oreo’s background limits. The ML model ran entirely on-device using a lightweight TensorFlow Lite model, with no data sent to the cloud. The feature improved over time as it learned usage patterns.
App Actions and Slices
App Actions predicted what you’d want to do next based on context and usage patterns, then surfaced those actions in the app drawer and launcher. Plug in headphones at 8 AM? The launcher suggested Spotify’s Discover Weekly playlist. Call a specific contact every Wednesday at noon? The Phone app shortcut surfaced that contact.
Slices were interactive app UI fragments that appeared in Google Search and Assistant results. Search for “Lyft to airport” and a Slice from the Lyft app showed pricing and ETA directly in the search results, with one-tap booking.
Both features were ambitious but underused. App Actions worked well enough but felt intrusive to some users. Slices required developers to implement a new API, and few did. Google eventually folded these concepts into Assistant integration.
Indoor Navigation (Wi-Fi RTT)
Pie introduced support for Wi-Fi Round Trip Time (802.11mc), enabling indoor positioning accurate to 1–2 meters. This was technical infrastructure for future features — indoor navigation in malls, airports, and museums — rather than a consumer-facing feature in Pie itself. The Pixel 4 (launched with Android 10) was one of the first phones to use Wi-Fi RTT for location.
User Interface Changes
- Pill navigation: The three-button bar was replaced (optionally) with a pill + back button. Swipe-based app switching and Overview were gesture-driven.
- Overview redesign: Overview showed full-screen app cards in a horizontal scroll, with a row of suggested apps at the bottom and a search bar. The UI was closer to iOS’s app switcher than any previous Android version.
- Rotation button: When auto-rotation was disabled but the phone was rotated, a small rotation icon appeared in the navigation bar, letting the user manually rotate without enabling auto-rotation.
- Screenshot editing: A screenshot markup tool appeared immediately after capture — crop, draw, highlight — without opening a separate app.
- Volume slider: The volume rocker now controlled media volume by default (not ringer volume), reflecting how most people used their phones. The volume slider appeared next to the physical buttons instead of at the top of the screen.
- Colorful Settings icons: Settings categories gained colored circular icon backgrounds for better visual distinction.
Performance Improvements
- Adaptive Battery: ML-driven battery management improved real-world battery life by 10–15% on the Pixel 2 and Pixel 3.
- ART optimizations: ART’s garbage collector was further refined, reducing GC pause times on lower-RAM devices.
- System tracing: Android Runtime profiling tools were improved, making it easier to diagnose performance issues.
Security Improvements
- BiometricPrompt: A unified biometric authentication dialog replaced the fragmented fingerprint and face authentication UIs. Apps could call
BiometricPromptand get a standardized dialog regardless of the biometric sensor type. - StrongBox Keymaster: Hardware-backed key storage with tamper-resistant hardware (for devices that supported it). StrongBox stored keys in a physically isolated, tamper-resistant secure element.
- TLS by default: Apps targeting API 28+ defaulted to HTTPS, with cleartext (HTTP) traffic blocked unless explicitly allowed.
- DNS over TLS: Private DNS mode enabled encrypted DNS queries to DNS-over-TLS providers.
- Lockdown mode: A power menu option that disabled biometric unlock and Smart Lock, requiring PIN/pattern/password.
Developer Features
| API | Description |
|---|---|
BiometricPrompt | Unified biometric authentication dialog |
ImageDecoder | Modern image decoding with animated image support |
android.net.wifi.rtt | Wi-Fi Round Trip Time for indoor positioning |
| Neural Networks API 1.1 | Expanded on-device ML acceleration |
| HDR VP9 Video and HEIF | High Dynamic Range video and High Efficiency Image File format |
| Multi-camera API | Simultaneous camera streams from multiple cameras |
| App Actions / Slices | Contextual app shortcuts and search-result embedded interactions |
| Magnifier widget | System-level text magnifier for text selection |
Devices That Shipped With Android 9 Pie
- Pixel 3 & Pixel 3 XL — Google’s third-generation Pixel. 5.5/6.3-inch 1080p/1440p P-OLED, Snapdragon 845, 4 GB RAM, 12.2 MP camera (still the best smartphone camera). The 3 XL had a massive notch that became a meme. Both phones had excellent cameras and mediocre battery life.
- OnePlus 6T — First OnePlus to ship with Pie. 6.41-inch 1080p AMOLED, Snapdragon 845, 6/8 GB RAM, in-display fingerprint sensor, $549.
- Samsung Galaxy S10 / S10+ — Launched with Pie and One UI (Samsung’s major skin redesign). 6.1/6.4-inch 1440p Dynamic AMOLED, Snapdragon 855 / Exynos 9820, 8 GB RAM, ultrasonic in-display fingerprint sensor, triple rear cameras.
- Huawei P30 Pro — 6.47-inch 1080p OLED, Kirin 980, 8 GB RAM, quad-camera with 5× periscope zoom. Launched with Pie and EMUI 9.1. The last Huawei flagship with Google Mobile Services before the US trade ban.
Comparison With Oreo
| Android 8.x Oreo | Android 9 Pie |
|---|---|
| Three-button navigation | Pill-based gesture navigation |
| No Digital Wellbeing | Dashboard, App Timers, Wind Down |
| Background execution limits | Adaptive Battery (ML-driven) |
| Notification channels | Notification channels + suggested replies |
| No indoor positioning | Wi-Fi RTT indoor positioning |
| Basic biometric APIs | Unified BiometricPrompt |
| API Levels 26–27 | API Level 28 |
Pie was braver than Oreo — willing to change fundamental interaction patterns, willing to admit that the platform could be addictive, willing to use AI for more than just photo enhancement. Not all of it worked: the gesture system needed two more years of refinement, App Actions and Slices never achieved broad adoption, and Digital Wellbeing was more of a self-awareness tool than a behavior-change tool. But Pie asked hard questions, and that mattered.
Legacy and Impact
Gesture navigation is Pie’s most visible legacy. The pill-based system was refined through Android 10 (full gesture navigation) and Android 12 (smoother animations, better tablet support) into the modern Android gesture system. Every Android phone sold today uses gestures that trace their architecture to Pie’s pill.
Digital Wellbeing normalized the idea that platform owners had a responsibility to help users manage their relationship with technology. Apple followed with Screen Time the same month. Third-party apps like Forest, Freedom, and One Sec built on the same concepts. The conversation about tech addiction and intentional use — now mainstream — was legitimized by Pie and iOS 12 integrating these tools at the OS level.
Adaptive Battery brought on-device ML to power management and set the expectation that AI would optimize system behavior proactively, not reactively. Android 10 and later versions expanded the concept, but Pie’s Adaptive Battery was the proof of concept.
End of Support
- Security patches: Last official patches for Pixel 3 were in late 2021.
- Play Services: API 28 (Pie) is still widely supported.
Fun Facts
- The last dessert name: Pie was the final publicly-branded Android dessert release. Google announced the rebranding to “Android 10” in August 2019, ending a decade-long tradition. The Building 44 statue was a slice of pie with the Android bugdroid.
- Easter egg: The Pie easter egg was a psychedelic animated “P” logo with trippy colors and patterns. Drawing a “P” on the screen in the easter egg launched a hidden drawing app.
- Pixel 3 XL’s notch: The Pixel 3 XL had one of the largest notches of any phone in 2018 — deep enough to fit two cameras and a speaker. It was so widely mocked that Google added a software option to “hide” it (by blacking out the status bar area, making it look like the phone had a thick bezel). The Pixel 4 abandoned the notch entirely.
- Not Pink color: The Pixel 3’s “Not Pink” color (officially called “Not Pink”) was a pale pink. The name was a joke from Google’s marketing team that stuck.
Frequently Asked Questions
What API level is Android 9 Pie?
API Level 28.
Why did Android stop using dessert names?
Google cited global accessibility: dessert names weren’t universally recognized (lollipop isn’t a word in every language, pie is an American-centric concept), and the alphabetical sequence created confusion about version order. The simpler “Android 10” branding was clearer for global audiences.
Was gesture navigation mandatory?
No. Pie’s pill navigation was optional — users could revert to three-button navigation in Settings → System → Gestures. Android 10 made full gesture navigation the default, but three-button remained an option.
What is Digital Wellbeing?
Digital Wellbeing is a set of tools that tracks app usage, sets daily limits, and reduces visual stimulation at bedtime. It’s designed to help users manage their relationship with their phone and reduce compulsive use.
Final Thoughts
Pie was the release where Android stopped being a spec sheet and started being thoughtful software. Gesture navigation was a bet that users would trade familiarity for efficiency. Digital Wellbeing was an admission that unlimited access to everything, all the time, wasn’t making people happier. Adaptive Battery was a promise that AI could make your phone work better without you managing it.
The features didn’t all land — the gesture pill was clunky, Digital Wellbeing didn’t meaningfully change behavior for most users, and App Actions never became the context-aware assistant Google envisioned. But Pie asked the right questions: How should you interact with a screen-only phone? How much phone is too much? Can your device predict what you need?
Android 10 would refine Pie’s answers. But Pie asked first.
Related Articles
- Android Version History (2008–Present)
- Android 8 Oreo: Complete Guide
- Android 10: Complete Guide
- The Evolution of Android Gesture Navigation
- Digital Wellbeing: One Year Later
- Pixel 3 & 3 XL: The Camera King
References
- Official Android 9 Platform Highlights (developer.android.com)
- Android Developers Blog: “Introducing Android 9 Pie” (August 2018)
- Digital Wellbeing launch documentation
- Adaptive Battery technical whitepaper (DeepMind/Google)
- Wi-Fi Round Trip Time specification (802.11mc)
- Google Pixel 3 / 3 XL product documentation