Apple App Site Association

When you support universal links, iOS users can tap a link to your website and get seamlessly redirected to your installed app without going through Safari. If your app isn’t installed, tapping a link to your website opens your website in Safari.

Universal links give you several key benefits that you don’t get when you use custom URL schemes. Specifically, universal links are:

• Unique. Unlike custom URL schemes, universal links can’t be claimed by other apps, because they use standard HTTP or HTTPS links to your website.

• Secure. When users install your app, iOS checks a file that you’ve uploaded to your web server to make sure that your website allows your app to open URLs on its behalf. Only you can create and upload this file, so the association of your website with your app is secure.

• Flexible. Universal links work even when your app is not installed. When your app isn’t installed, tapping a link to your website opens the content in Safari, as users expect.

• Simple. One URL works for both your website and your app.

• Private. Other apps can communicate with your app without needing to know whether your app is installed.

https://developer.apple.com/library/content/documentation/General/Conceptual/AppSearch/UniversalLinks.html