I know that this is really basic, but since this is a new tag and technology, I hope you'll permit the question.
Having just discovered the existence of WinObjC (the Windows Bridge for iOS project) I want to understand what I can do with this before I start to devote time to it.
The following project description is a little confusing to me:
The Windows Bridge for iOS (also referred to as WinObjC) is a Microsoft open-source project that provides an Objective-C development environment for Visual Studio and support for iOS APIs. The bridge allows you to create Universal Windows Platform (UWP) apps that will run on many Windows devices using iOS APIs and Objective-C code alongside Windows 10 features like Cortana and Live Tiles.
I mean, I see it says for iOS but OTOH it says that it allows you to create UWP apps that run on many Windows devices. I am embarrassed to say I find this confusing.
I feel 90% sure that it is not for developing iPhone apps, but a 10% chance I can develop for iPhone without being able to buy a new enough Macbook is enough to make me ask this question.
The Windows Bridge for iOS allows you to build UWP apps by reusing code you wrote for an iOS app. Say, for instance, you wrote an iPhone game; you could use the bridge to turn it into a UWP game that runs on Windows desktops, laptops and touch-screen devices. You could also use the bridge to add Windows-specific features like Live Tiles and Cortana integration.
If you'd like to develop for iOS without having to buy a new MacBook, you might want to check out another Microsoft project called Xamarin which allows you to do cross-platform mobile development right from Visual Studio.