I want to do some cross-platform mobile development (Android, iOS, Windows Phone) using Xamarin, the problem is that I only have an android device and a windows machine. But I still want to be able to test my apps for iOS and I can't really buy a mac (and/or an iphone) just for this. I'm thinking about testing my apps using Appetize.io, but to do that I would still need a MAC machine to be able to build the app and upload to appetize. Is there any workaround for that?
You need Xcode to build, sign and upload your app; it also is advisable to test it on real hardware (aka an iPhone) before releasing it. Xcode is only available for macOS though so you need at least a small Mac mini for this (which is more than enough for smaller apps)