Q:

Should [swift] and [objective-c] tags never be used together?

I recently asked a question using the tags ios objective-c swift textkit
However, the objective-c and swift tags were edited out. I'm fine with that because I can see how the ios tag covers them both already. Also, the editor (rmaddy) is a high rep user with gold badges in ios and objective-c so this user obviously know what they are doing. A month ago rmaddy even asked the meta question What is the cause of so many Swift questions getting tagged with Objective-C? (but is as yet unanswered).
So I want to know, should I never double tag these languages as long as I use the ios tag? I'm not really sure because, to my thinking, there may be some advantage to including the language tags in addition to the platform. For example

Some people who could answer the question may not be following ios
Lets the question be searchable by both objective-c and swift.
Explicitly shows that both Objective-C and Swift answers are acceptable.
Although possibly superfluous, the extra information does not falsely represent the content of the question.

A:

I agree with rmaddy's edit, and here's why.
Language tags should be used when knowledge of the language is essential to understanding the problem and its solution. They say "this question is about something in this language".* If both truly apply, then you must be asking about some kind of cross-over situation (which is definitely possible). There's no Swift or ObjC code in your question, and if you don't care which language is used, then really neither is essential to your problem.
You're asking about an API; that API is accessible in several languages, including ObjC, Swift, C#, and Python. If a MonoTouch dev comes along, she can look at your question and say "You basically have to do the calculation yourself; ask the layout manager for its foo and then..." just as well as someone who knows the framework via ObjC or Swift.
Also importantly, long-term, everyone else with the same problem -- including the people using Ruby or Nu when someone gets around to making those work on iOS -- will find answers that just talk in terms of the API more helpful than one that is in a language they don't care to use.

*See also: https://meta.stackoverflow.com/a/289234/

