Apple Shares Requirements for Default Third-Party Browser and Email Apps With Developers
Apple hasn't provided many details on the new feature to users, but as noted by MacStories' Federico Vittici, Apple has shared documentation with developers who want their apps to have the option to be set as a default email or browser app.
According to Apple, developers will need to meet certain guidelines and when those parameters have been met, there's an option to request a managed entitlement that will allow the app to work in lieu of Apple's own apps.
Default browser apps must provide a text field for entering a URL, search tools for finding relevant links on the internet, or curated lists of bookmarks. When opening a URL, apps must navigate directly to the specified destination and render the expected web content without redirecting to an unexpected location.
Apps designed with parental controls or a locked down mode can, however, restrict navigation. Email apps set as default must be able to send a message to any valid email recipient and must be able to receive a message from any email sender. Apple says that apps that offer user-controlled incoming mail screening features are allowed.
Third-party browser apps set as default will open up automatically when a URL is tapped instead of the Safari app, while third-party email apps will open when a mailto: link is tapped.
Apple's full documentation can be found on its developer website. Apps will need to be updated with entitlements to be able to be set as the default browser or mail app in iOS 14, so no apps have that functionality at the current time.
We should begin seeing apps able to replace Mail or Safari as default apps close to when iOS 14 launches this fall.