I know that all iOS apps must be built on a Mac before they can be submitted to the App store but I've noticed that Visual Studio App center provides build services - even for iOS.
Can this be used for beta testing purposes or do I still need a Mac to do the build even for beta testing purposes?
BTW, the app is an enterprise Xamarin Forms app for internal use.
Yes, you also need Mac for Beta testing. But I use https://www.macincloud.com for testing rather then buying Expensive hardware.
It has built in Support for Xamarin and it very cheap.
iOS not like Android you also ned Apple Developer Lic. for distribute your app. you can purchase your Lic. as your Requirement from hear : https://developer.apple.com/support/compare-memberships/
(if you just want to check how look your app in Device you can use Xamarin Live )
ipasigned with a provisioning profile from your Apple developer account and push it aDistributeall on Azure. IMHO if you are not locally building/testing on physical devices, you will be spinning your wheels trying to figure out why it is not working in a tester's device (unless it is a really simple Forms app using no network access and no iOS specific permissions or device features) ;-) - SushiHangover