You can use VSCode, but you should install Xcode regardless of what development environment you desire using. For one thing, Xcode comes with the SDKs. These can be installed separately through a command line tool, Xcode-select --install, which will just install the build tools off of Xcode. However, Xcode also comes with Simulators so you can test your iOS apps, tvOS, watchOS apps on your Mac. Without the Simulators from Xcode you can only run the Mac apps, not iOS code. Xcode also includes the necessary utilities to push the app you develop to a real device and a nice documentation viewer for Apple's frameworks, as well as Instruments for analysing your app, tools to analyse usage data from App Store reports and more. In short, Xcode is not just the IDE, but a whole suite of utilities many of which are universally recommended regardless of which editor/IDE you choose to use