Unity vs SceneKit: which tool you should use to build your ARKit app
MacOS, Linux, Windows 10
Xcode is better if you are planing to make an app where AR is a feature. If you are planing to make cross-platform development, a lot of 3D content, special effects, and other game related things Unity is better.
Apple is offering 2D components like buttons that follow Apple's guidelines making sure the design is really good. Achieving the same quality with Unity requires much more work. Then in games there are not that much components you can take from Apple so it totally makes sense to use Unity as it contains things like physic calculations and better animations.
Unity is better for game development while Xcode is better for utility apps.
The Match-up: SceneKit or Unity for ARKit? | Hacker Noon
ARKit doesn't seem to have as good 3D editor as Unity allowing only do small things like rotate, position, change material, etc. but otherwise it needs to be done from the code.
Unity is better for quick prototyping but I believe it's even better to use something simpler https://www.notion.so/lankinen/AR-designing-cb85797b670e45f483422ff43886dd88 and then after that Xcode if the other reasons don't lead to Unity.
It seems like Unity is good for game development but Xcode wins when doing apps. The reasons seemed to be that it offers 2D components but as soon as the apple glasses are released, I believe that the platform will become better to develop only 3D content as the glasses probably don't have buttons.