weights or cardio first?

Which should I do first? 

I figure I'll work legs on days I swim for cardio and work arms on days I walk for cardio.  I'm just not sure which I should do first.  I'm not sure I CAN do weights AFTER swimming .....

Thanks!!

I'm not sure what you mean by "first". Do you mean first in the day? It really doesn't matter. People will tell you it's better to do one first or the other but there are no studies that show that. It's really what works for you.

For me, I do strength training on days I swim or days I don't do anything else. Plus I take at least one day off a week.

Just my opinion. If you are training for an event make that your primary focus. If you are just working out for weightloss or general health I would do the weights first so you can lift heavier when your not as tired.