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Folding smartphone rumors have given way to tech demos – and 2019 looks like the year of foldables. But what does this mean for mobile app developers?

Samsung’s foldable screen has seen the light of day

Samsung shared their upcoming foldable OLED display at the Samsung Developer Conference (SDC) earlier this month. Sadly, the phone itself was hidden in shadow.

The new Super AMOLED ‘Infinity Flex’ screen features a 420dpi ‘cover display’ that unfolds into a double-sized ‘main display’. Apparently, it’s thin and can tolerate being folded ‘hundreds of thousands of times’ – and will be ready for mass production in 2019. And The good news is that Samsung will open up an emulator SDK to let developers test their apps and offer guidelines on how to develop mobile apps for foldable devices.

Cover Display

  • 4.6-inches
  • 840×1960 resolution
  • Smallest screen width: 320dp

Main Display

  • 7.3-inches
  • 1536×2152 resolution
  • Smallest screen width: 585dp

Android is ready to make your app foldable

Google also said they’re working with handset manufacturers – including Samsung – to ensure Android supports foldable devices. On the same day at the Android Developer Summit, Google officially announced the Foldable support on Android phones by using its ‘screen continuity’ API.

‘[Google is] enhancing Android to take advantage of this new form factor… ‘[We’re] already working closely with Samsung on a new device they plan to launch early next year.’
Dave Burke, VP of Engineering for Android


Foldable support sounds surprisingly simple

Android developers already create multiple layouts and assets so that apps can scale across smartphones and tablets with a range of resolutions, dimensions and pixel densities.

‘This new form factor is therefore simply adding new use cases to this existing pattern.’
– Sagar Kamdar, Director of Product Management at Google

Android’s ‘screen continuity’ API informs apps when the device’s screen size or resolution has changed so that it can adjust the layout. Users already experience this behavior whenever they rotate their display and the app switches between landscape and portrait mode. As far as Google are concerned, foldable screens will simply represent a new layout and be treated as a single display.

What does foldable mean for developers?

In a nutshell, this means more space for detail and immersive experiences. Your app’s ‘cover layout’ might contain highlights or a focused view, while the ‘main layout’ allows extra details and features.

Video streaming and gaming apps can simply increase their screen size – or instead, use the extra space to offer additional information and controls. Some must-have apps for daily use will see some impact.

  • Calendar: open up a whole month instead of a week.
  • Banking: show all your accounts at once, instead of just one.
  • Emails: open a large preview pane next to your inbox.

Multi-Active Windows take dual-screens further

Samsung also unveiled a feature called ‘Multi-Active Windows’ that allows up to three apps to run at once. This simply extends the core benefits of dual-screen and change the way mobile users interact with their phones and apps.

  • Gamers: live-stream their friends and use social media while playing.
  • Business users: use Slack while reading documents and emails.
  • Content creators: bounce their creations between apps.
  • Anyone: video-chat while reading or watching another app.

Early dual-screen phones lacked the processor horsepower to take full advantage of their potential. And it’s foreseeable that Multi-Active Windows show how far we’ve come since then.

‘We’ve always strived to bring you meaningful breakthroughs. But despite all of that progress, we’ve been living in a world where the size of your screen can only be as large as the device itself.’
Hassan Anjum – Director of Product Marketing , Samsung

Bigger screens, more market disruption

Smartphone screens keep getting bigger – and they’re not wasted on consumers. Apple’s original iPhone had a 3.5-inch 320×480 screen, whereas this year’s XS Max boasts a 6.5-inch 2688×1242 display.

Certainly, foldable phones will remove the pocket-friendly bar and should spur a leap in average screen-sizes. But what’s the point? Cynics might suggest that bigger screens are just marketing material. But it’s clear that apps continue to grow in popularity and disrupt markets.

Mobile banking competition is heating up

Mobile banking seems the obvious explanation – Europe’s number of domestic bank branches have declined year-over-year since 2008, the year after the original iPhone was released.

Number of Domestic Bank Branches

Part of the reason could be that the rise of challenger banks since 2014 has disrupted the banking industry and driven competition for online banking features. So it’s little surprise that mobile banking will overtake online banking in 2019, according to a report by Financial services analyst CACI.

Now foldable handsets will offer a great opportunity to upgrade the user experience for mobile apps in competitive sectors like banking, so we should expect this trend towards digital to continue.

Dual-screen Android devices aren’t new

Launched in 2011, Kyocera’s Echo was ‘The world’s first dual-screen smartphone’ with dual 3.5-inch WVGA screens, running Android 2.2 Froyo. The device could imitate a single 4.7-inch screen in ‘tablet’ mode, or run separate apps on each screen.

However, developers had to use proprietary build systems and documentation to make full use of both screens. Kyocera even had to recruit developers including EA, Gameloft and Jibs to use its development kit, to try and show-off Echo’s capabilities.

Kyocera Echo

Pixel densities have come a long way – ZTE’s Axon Mlaunched in late 2017, sports Dual 5.2-inch 1080p screens and runs Android 7.1 Nougat. The phone can form a 6.75-inch screen with a 2160×1920 resolution using its two screens.

ZTE Axon M

Developers can take advantage of the Axon M’s screen modes by simply creating new layouts that applications and games automatically accommodate. For example, YouTube’s app places videos on one screen and shows information and comments on the other.

Some applications don’t have appropriate layouts yet and therefore behave unpredictably. But this isn’t a new problem – many mobile apps scale badly on tablets because they haven’t been optimized for Extended Mode resolution.

2019 will be the year of foldable smartphones

Samsung has plenty of competition for 2019, with most major Android smartphone manufacturers planning foldable devices. And In fact, Samsung probably won’t be first to market:

Royole, a California-based company, claims that their handset FlexPai to be shipped in December will be the first foldable smartphone, although only for the Chinese market, at least initially. The device will sell for around $1,300 and includes a 4-inch AMOLED screen that unfolds to 7.8-inches. It runs Android 9 Pie (with the company’s Water OS UI) and is powered by the upcoming Snapdragon 8150 (an unannounced 7 nanometre and 8-core processor with a dedicated neural processing unit for AI-powered tasks).

Royole Flexpai


Samsung has a foldable smartphone lurking in the shadows. However, internet rumors are divided over whether it will be called a ‘Galaxy X’, ‘Galaxy F’, or “Galaxy Flex’. But we do know that it’s got a 4.6-inch ‘Infinity Flex Display’ that unfolds to 7.3-inches.



Leaks suggest that Huawei will launch a foldable smartphone with 5G capabilities and a 5-inch screen that unfolds to 8-inches, and it’s targeted for a June 2019 launch. No commercial 5G networks have launched yet, although South Korea is likely to be among the first countries to launch a 5G service. Nonetheless, extensive 5G testing will be required.

And here’s more,

  • LG has publicly discussed their plan to launch a foldable phone and filed a number of patents relating to foldable technologies. Rumors suggest an unveil at its CES Keynote in January.
  • Apple has filed its second patent for a foldable phone – featuring an unusual front-to-front folding configuration.

It’s clear that most major smartphone manufacturers will be launching foldable devices in 2019. Whether this is a major new technology or – like 3D TV – a passing fad, will likely depend on the benefits that developers can leverage.

  • What benefits will foldable devices offer your current applications?
  • How will foldable smartphones change your approach to app development?
  • Are foldable phones just a fad or here to stay?

Alex Napier Holland

Tech Business Writer