First, I probably wouldn't use a framework like this unless it was really compelling. There are plenty of free versions of most of those components on cocoapods or github. I'm sure yours are better, but I can just pod install one of those and not have to worry about buying a license and get my task done. Would strongly suggest that you have some way to use parts of the framework incrementally, and maybe have some of them free and others of them "premium".
Also, cocoapods. If I can try out a component from a cocoapod, that means I can probably drop it into my app in 5-10 minutes, then if it's interesting spend a few hours seriously evaluating it. If I have to run some kind of installer, and then start a new app with a strange xcode template, I'm just not going to do it. Maybe that's just me, maybe other devs will.
I would suggest a non-invasive, per-app license, along with an expensive option for the perpetual license for enterprises or very prolific freelancers (or agencies).
Don't do any complicated nonsense with license keys and BS like that. It's a huge headache for you and for the developers, and pirates are going to get around it anyways. Just let anyone link your sdk, and have a way to identify apps that use your components (e.g. print [Trial Version] or something to the console). If someone uses your components on a popular app, check if they have a license and let the lawyers handle it. If small developers use your components just don't worry about it, it's more trouble than it's worth to go after. Offer a very generous discount for small devs to put your logo on their splash screen, that might convert some would-be pirates to organic marketing.