Apple's Software Chief Details How iOS Apps Will Run on Macs

In an exclusive interview, Apple's Craig Federighi explains how developers will be able to get their apps working on both platforms.
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Apple's Craig Federighi on stage at WWDC 2018 Monday.David Paul Morris/Bloomberg

Near the end of yesterday's WWDC keynote, Craig Federighi, Apple's senior vice president of software engineering, acknowledged that people have been asking for a long time whether Apple would ever merge the iPhone and Mac operating systems. His short answer? "No." The word "No" appeared in giant white letters on the colossal screen behind him. Within minutes, screenshots of the "No" had populated Twitter, some with memes attached.

Except, that "No" should have had an asterisk after it, because while Apple still plans to ship two distinct operating systems—one for mobile, one for desktop—the company has been working on bringing iOS apps to Mac hardware. In an exclusive interview with WIRED, Federighi said the frameworks for porting iPhone and iPad apps to the Mac have been in development for two years. He revealed some of the technical details around how this will work, and shared some of the types of iOS apps he believes make sense on the Mac. Federighi was also dismissive of touchscreen laptops—a product category that would seem like a natural addition to Apple's line once laptops begin running touch-first mobile apps.

Double Standard

The point of this is not to create a single unified OS, Federighi said. But the fact that Apple spoke openly about an initiative that could arrive as late as a year from now is a clear nod to how the tech giant perceives the future of apps. It also says something about the health of the Mac's App Store, which has tens of thousands of apps but remains dwarfed by the the mobile App Store, which boasts millions of apps.

At WWDC on Monday, Apple said some of its homegrown iOS apps, including Home, Stocks, News, and Voice Memos, would be available later this year on MacOS Mojave, the next version of MacOS. On the surface, it seems obvious that Apple might make some of its own apps available across different platforms. But behind the scenes, Apple has been building tools third-party developers can eventually use to port their own apps from iOS to MacOS with what Federighi insists will be minimal effort. Apple began this initiative around two years ago, and its own internal software engineers have been beta testing the tools. These four iOS apps for Mac are the products of that testing.

These efforts had been rumored before. Bloomberg reported at the end of last year that Apple was working on some sort of solution to let app makers build a single app that could run across both iOS and MacOS. But there were still questions about how these multi-platform apps would be developed and how certain interactions would work; using an iPhone touchscreen is different from using a mouse on on a Mac, for example.

Native Tongues

At a high level, Federighi described what Apple is doing as bringing an iPhone software framework over to Mac and making it native to Mac, rather than using some type of simulator or emulator. Both iOS and MacOS share a common kernel and have common sets of frameworks for things like graphics, audio, and layout display. But over time, each platform has evolved differently. The biggest and most well-known framework is UIKit, but that was built for iOS way back at the start and wasn't designed to address mouse and keyboard controls. With MacOS Mojave, UIKit will be updated. Just like developers are currently able to target an iPhone or an Apple TV as the device where their app will run, they'll soon be able to target the Mac as well.

For app makers, some aspects of app porting will be automated and others will require extra coding. Using Xcode, Apple's app-making software that runs on Macs, a developer will be able to indicate they want to write a variant of their iOS app for MacOS. Certain interaction UIs will happen automatically, like turning a long press on iOS into a two-finger click on a Mac. App makers may have to do some extra coding, though, around things like menus and sidebars in apps, such as making a Mac app sidebar translucent or making share buttons a part of the toolbar.

Even though the apps are effectively being shared between operating systems, Federighi emphasized that your Mac won't start behaving like an iPhone. "It's still MacOS, you still have the Terminal, you can still attach four monitors to it, you can still hook up external drives," he said.

Not every kind of mobile app will make practical sense on a Mac. You're not going to pick up your Mac and walk down the street using motion sensors to track your physical activity, for example. But Apple believes that many games will easily be able to make the leap; Federighi specifically mentioned Fortnite as a candidate for porting. He also said he could picture certain websites like IMDB, Yelp, or DirectTV having native desktop Mac apps.

Of course, developers are able to make these apps for MacOS now. It's just more work, given the current toolset. And on the user side, there would have to be some sort of value add, whether it's specific app features or even privacy concerns, for a person to want to download and hangout in a desktop app rather than quickly look up a restaurant or a movie in the web browser.

I asked Federighi whether the fact that iPhones and Macs run on different chip architectures would impact how the same app runs across both devices. "At this level, not so much," he said. "In a lot of our core APIs, things like Metal, we've done the hard work over the years of making them run well on both Mac and its associated CPUs and GPUs, and on iOS."

Touchy Subject

When addressing my question about whether iOS apps moving to MacOS is a natural precursor to touchscreen Macs, Federighi told me he's "not into touchscreens" on PCs and doesn't anticipate he ever will be. "We really feel that the ergonomics of using a Mac are that your hands are rested on a surface, and that lifting your arm up to poke a screen is a pretty fatiguing thing to do," he said.

Federighi added that he doesn't think the touchscreen laptops out there today—which he referred to as "experiments"—have been compelling. "I don't think we've looked at any of the other guys to date and said, how fast can we get there?" (It's worth noting that Microsoft's Surface laptop, which has a touchscreen and is considered a top MacBook rival, has received largely positive reviews.)

Universal Future

Speaking of competition, Apple's biggest competitors in mobile and desktop software are both already offering some version of mobile apps that can run on laptops and desktops. Microsoft's Universal Windows Platform, introduced back in 2016, lets developers write just one app and have it run across PCs, tablets, mobile phones, and the XBox One. That same year, Google said it was bringing the Google Play app store to Chromebooks, which meant people could download and use Android apps on their ChromeOS computers.

Microsoft and Google have different technical approaches to running similar or the same versions of apps across different devices. But both systems are an acknowledgement of a basic truth: While people really love mobile apps, it can be inefficient and costly for developers to have to build entirely separate apps for multiple platforms.

Also, the concept of universal apps, or mobile apps on PCs, have not been unilaterally embraced. Shortly after Microsoft announced UWP, one developer spoke out against what he saw was an aggressive and overly controlling move on the part of Microsoft. Epic Games cofounder Tim Sweeney wrote in an op-ed that the company was "effectively telling developers you can use these Windows features only if you submit to the control of our locked-down UWP ecosystem."

There's also the question of what universal apps mean for revenue splits, since Apple gets a 30 percent cut of all revenue from apps sold in the App Store (or in the case of long-term subscription apps, 15 percent). Right now Mac developers can distribute their apps on the web and avoid Apple's fee structure. Will developers have the same level of control if they're creating a MacOS app from an iOS app?

Federighi insisted that how an app is distributed and how much it costs will still be up to the developer.

But again, all of this isn't happening until next year, so there are a lot of details still to be shared, and likely a lot more conversation about the value of desktop apps versus web apps. I asked Federighi when, exactly, third-party developers would get access to these tools. He declined to say. But when I asked if it would be reasonable to think that this is something we'd hear more about in a year—at WWDC 2019—he replied: "That would be a reasonable thing to think."


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