Swift alternative for #pragma clang diagnostic

As of version 2.0 (currently in beta as of this writing), Swift still does not include a preprocessor and that doesn't look to change anytime soon (if ever). The beneficial abilities that preprocessors allow are built into the language itself in various ways (I won't cover all of them here, see the docs) and are compile-time level features.

There are two features I do want to mention (one old, one new) that may be what you're looking for:

1. Conditional Compilation - As covered in Using Swift with Cocoa and Objective-C, you can implement conditional compilation statements that allow you to only compile code given certain operating systems or processor architectures. If looks something like this:

2. Checking for API Availability - As covered in The Swift Programming Language, you can now check for API availability based on platform and OS version. This will allow you to take advantage of newer API's while allowing you to handle when that feature isn't available on an older (or different) platform or OS. You could use this to sub in an alternate implementation or present an explanation to the user. If looks something like this:

These tools (along with many others built into the language) should allow a developer to replace the Objective-C and C preprocessor macros. Personally, I think they are a huge improvement.