For apps that don’t require iPad-only features, the best way to ensure that your app will work well on a Mac is to make sure it works well on iPad. In particular, your app should:
* Support multitasking. Apps that do a good job scaling the interface to support Split View, Slide Over, and Picture in Picture approach the ultimate goal of supporting the extensive window resizability that Mac users expect.
* Support drag and drop. When you support drag and drop in your iPad app, you get the same support on the Mac for free.
* Respond to keyboard shortcuts, including common macOS shortcuts. Even though a keyboard may not always be available to your iPad app, both iOS and macOS users appreciate using keyboard shortcuts to streamline their interaction with your app.

Before You Start

The conventions and design patterns that have the biggest impact on adaptation can be grouped into four key areas.
* Navigation. Many iOS and macOS apps organize data in similar ways, but they use different controls and visual indicators to help people understand and navigate through the data.
* User input and interactions. Although both iPad and Mac accept user input from a range of devices — such as the Multi-Touch display, keyboard, mouse, and trackpad — touch interactions inform iOS conventions, whereas keyboard and mouse interactions originated the conventions for macOS.
* Menus. Mac users are familiar with the persistent menu bar and expect to find all app commands in menu bar menus. iOS, on the other hand, doesn’t have a persistent menu bar, and iOS users expect to find app commands in the app’s UI. 
* Content scaling. Text in the macOS version of an iPad app looks the same as it does in iOS because SF fonts are available on both platforms. However, the baseline font size in iOS is 17 pt, whereas the most common font size in macOS is 13 pt. To ensure that your text and interface elements are consistent with the macOS display environment, iOS views automatically scale down to 77%.

Plan Enhancements for Your Mac App

University of Michigan - Ann Arbor

IOS - Human Interface Guidelines are "software development documents which offer application developers a set of recommendations." Their goal is to improve the user experience by making more intuitive and consistent application interfaces. 

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