What situation would it be better to use a struct in, over a enum?

Enums in Swift are insanely awesome. So this answer may not be aligned to ther languages, but for Swift it is valid.

Enums are great for safety!!! The finite nature of them make them fantastic for objects that are taking input from the user. So first and formost, if you are taking something in from the user and you need it to be safe, enums are for you! Enums are also great for storage. Being able to use things like Ints for associated vlaues mean that you can have your objects respresented in persistant storage with a whole lot less space. Makes it great for iCloud type solutions too. Less data is good!

Now if the enum is not the right choice, then it comes down to a struct or a class. You'd choose a struct when inheritience is not required. Where each object stands alone. You'd use a struct where you are going to pass around individual items of unrelated data. So if you need to have objects that standalone and are unrelated, structs are great for that.

Remember, there are COUNTLESS other reasons that help guide your decision about which object type to use. But these ones above are often the most comon ones you will encounter at beginner and intemediate programming levels.

I hope this helps. And please, if you are an boss level programmer and you see errors or shortcomings in my not boss level info above, PLEASE correct me!!! I want to learn too!!! :)