Test on iPhone Duo: Apple's First Foldable Is Now Live on TestMu AI Real Devices

Apple says the 7.6-inch inner display on the iPhone Duo is 50 percent larger than the iPhone 18 Pro Max, while the 5.4-inch outer display gives you 90 percent of the screen area of an iPhone 18 Pro, according to its iPhone Duo announcement. So one app now has to look right on two very different screens, and keep working while someone opens or closes the phone.

You can now test on iPhone Duo in TestMu AI without buying one. I checked what was available on October 26, 2026, ran Safari on the iPhone Duo simulator, and wrote down what each option can do today.

Is iPhone Duo Available on TestMu AI?

Yes, the iPhone Duo is on TestMu AI in two forms, a real device and a simulator, and each suits a different kind of test. Apple ships the phone with iOS 27.1, which is why the simulator runs iOS 27.1 while the real device list labels the OS by its major version, iOS 27.

The list of real devices showed the iPhone Duo on iOS 27 with live testing switched on and automation switched off when I checked it. For quick checks without hardware, Real Time Testing runs the simulator: select Virtual Mobile under Web Browser Testing, choose iOS and the iPhone Duo, enter a URL, and click Start.

How Do I Test on iPhone Duo in a Live Session?

A live session streams the real iPhone Duo to your browser, and your taps, swipes, and typing go straight to the phone. The TestMu AI real device cloud gives you 50,000+ real Android and iOS devices, and it keeps the typical round trip under 150 ms on a standard connection, so the phone feels close to the one in your hand.

• Log in, open Real Device in the left sidebar, and pick Browser Testing for a website or App Testing for an app.
• Choose iOS, then search for the iPhone Duo in the device list.
• For App Testing, upload your app or install it from the App Store, TestFlight, or App Center. For Browser Testing on iOS, you type the URL once the session has started.
• Click Start, and use the Tunnel option in the top-right corner first if your build or site only runs on your local network.

The setup guides for browser testing on real devices and app testing on real devices walk through each screen. During the session you get Safari Web Inspector, device logs, and a network monitor, and every session gets its own freshly wiped device, so nothing carries over from the last tester.

What Does a Web Page See on the iPhone Duo Outer Display?

On October 26, 2026, I ran Safari on the iPhone Duo simulator (iOS 27.1, Appium 3.7.0) under the build name iPhone Duo Launch Viewport Check. I loaded the Selenium Playground, read the values below with JavaScript, and set viewport-fit=cover before reading the safe-area insets. The session opened with the phone closed, on the outer display.

The screenshot shows where the missing width went. The clock, Wi-Fi status, back button, Reader, and tab controls sit in a column on the right, which matches Apple's note that app navigation and controls now appear on the side, and that column takes 84 points of the 466-point screen. The iPhone Duo tech specs list the outer display at 1398 x 2034 pixels and 460 ppi, which is exactly what the screen values work out to.

The user agent read iPhone OS 18_7 with Version/27.0, so nothing in it tells you the page is on an iPhone Duo. The iPhone 18 Pro launch tests found the same frozen OS token on iOS 27, so lay out with media queries and never with user-agent checks.

What Should I Test First on iPhone Duo?

Start with the things that are new on this phone. Apple's iPhone Duo developer update says that because both displays share the same aspect ratio, apps transition smoothly from the outer display to the inner display. That smooth handoff is exactly what your users will expect from your app too.

• Open and close - Start a form or a checkout on the outer display, open the phone, and check that the text you typed, the scroll position, and any open dialog are still there.
• Size classes - In Apple's Prepare your app for iPhone Duo talk, the outer display reports a compact horizontal size class in portrait and the inner display reports regular width and height. A sidebar or second column should appear only when the phone is open.
• Split View - Apple says iPhone Duo lets people open two apps side by side on iPhone for the first time, so check your layout at a narrow width with another app next to it.
• Side controls and safe areas - The same talk warns that safe areas are often asymmetric and that vertical buttons can appear on the left side in landscape and Split View. Make sure no button or price sits under them on either side.
• Touch ID - Apple builds Touch ID into the side button, so re-run any sign-in or payment flow you only ever tested with Face ID prompts. For uploaded apps on iOS 13 and later that call LAContext, biometric authentication on real devices lets you pass or fail the prompt during a live session.
• Camera preview - Apple added camera APIs for taking selfies with the rear cameras, so if your app opens the camera, check the preview and capture on both displays.

Android foldables raise the same questions, and the guide to testing foldable phones covers the general pattern of screen states and continuity.

Note: Book a real iPhone Duo on iOS 27 for the Touch ID, camera, and open-and-close checks above. Try TestMu AI free on a real iPhone Duo

Which iPhone Duo Checks Need the Real Device?

Apple's talk tests every pose in the Xcode 27.1 Device Hub, with buttons to open, close, rotate, or fold the simulated phone, and it never mentions physical hardware. That makes the simulator great for layout, and it leaves the hardware checks for the real iPhone Duo. Here is how I split the work:

The speed row matters because Apple's developer update promises up to 35 percent better sustained performance than the iPhone 17 Pro, so frame-time baselines from older iPhones no longer describe this phone. For early layout checks on other iPhones, the iOS simulator online needs no Xcode setup at all.

Can I Automate Tests on iPhone Duo?

Yes, you can automate tests on the iPhone Duo simulator today. The TestMu AI capabilities generator lists the iPhone Duo simulator on iOS 27.1 with Appium 3.7.0 as its only Appium version, and that is the setup I used for every reading in this post.

Install the driver with npm install selenium-webdriver, then export LT_USERNAME and LT_ACCESS_KEY with the username and access key from your TestMu AI account:

const { Builder } = require("selenium-webdriver");

const capabilities = {
  browserName: "Safari",
  "LT:Options": {
    username: process.env.LT_USERNAME,
    accessKey: process.env.LT_ACCESS_KEY,
    platformName: "ios",
    deviceName: "iPhone Duo",
    platformVersion: "27.1",
    isRealMobile: false,
    appiumVersion: "3.7.0",
    build: "iPhone Duo Launch Viewport Check",
    name: "iPhone Duo simulator",
    w3c: true
  }
};

(async () => {
  const driver = await new Builder()
    .usingServer("https://mobile-hub.lambdatest.com/wd/hub")
    .withCapabilities(capabilities)
    .build();
  try {
    await driver.get("https://www.testmuai.com/selenium-playground/");
    const reading = await driver.executeScript(
      "return [innerWidth, innerHeight, screen.width, screen.height, devicePixelRatio];"
    );
    console.log(reading);
  } finally {
    await driver.quit();
  }
})();

When I ran it, the script printed [ 382, 580, 466, 678, 3 ], the same outer display values as the table above. If your suite already runs on Appium, the post on what's new in Appium 4 covers the multi-display commands the XCUITest driver added for the iPhone Duo.

Summing Up

Open a live session on the real iPhone Duo, load your busiest page, and compare its width with the 382 px I measured on the outer display. Then run the open-and-close and Touch ID checks from this post while the phone is still in front of you.

For the rest of this release cycle, see what changed in the iOS 27 release and the Galaxy Z Fold8 launch on Android 17, which covers the same open-and-close checks on Samsung hardware.