Craig Hockenberry of The Iconfactory has an in-depth look at the challenges developers, designers, and marketers will face bringing their iOS apps to the Mac. Although Marzipan may make it possible to simply flip a switch in Xcode to build Mac and iOS versions of an app simultaneously, it’s unlikely to be that simple in practice. As Hockenberry notes:

that build setting is just the first step on a long and complicated road. Good interaction doesn’t come for free.

That’s because user interactions are different between iOS devices and Macs and driven by multiple factors including differing input devices, screen sizes, and individual UI elements.

One of the many examples of design challenges that Hockenberry covers is moving from iOS device screen sizes to Mac screens:

The most obvious design element that will change as you move from iOS to macOS is the screen. If you’ve designed for the iPad, you already understand the challenges of a larger display surface and adapting your views as that size changes. It’s not easy work, but an alternative design that’s just “a big iPhone” is highly unsatisfying for a customer.

The Mac alters this scenario slightly because your app is presented in a window that’s resizable: you might be running with the constraints of an iPhone SE one moment and the expansiveness of an iPad Pro the next.

Hockenberry also raises concerns about how developers will make money from Marzipan apps if they are universal apps as is the case with the iPhone and iPad versions of many iOS apps:

It’s my opinion that Universal apps were the worst thing to ever happen for the iPad ecosystem. There’s no way for a developer to recoup the costs for new interactions and the extra work needed for more sophisticated apps. Apple makes it easier for a customer up front by offering a single download, but at the same time they make things worse because a Universal version of the user’s favorite app isn’t financially viable.

One thing’s for sure, change is coming to the Mac. For some, it will be exciting, and for others, it will be fraught with peril. Mistakes will be made, and adjustments will be necessary, but for iOS developers, designers, and marketers new to this sort of transition, Hockenberry’s post is a great place to start thinking about bringing their apps to the Mac. He’s been through similar changes in the past, and with the magnitude of what Apple likely has in store at WWDC, there’s no time like the present to start considering these issues.