Why don't you make any mention of ___domain knowledge relating to frameworks in your hiring criteria?
You state that "a good programmer can learn a language quickly". I think most people who have experience with hiring developers disputes this. Learning a language is also one of the easier hurdles to overcome when moving into a new programming ___domain.
If you're hiring for a Ruby on Rails team, and you want to hire someone who has prior experience as a developer but has never touched Ruby in their life, you're probably not going to be too worried about how quickly it will take them to learn Ruby. The real challenge will be learning Rails, and then becoming proficient enough to work alongside the current development team and the pre-existing codebase.
Also, how do you approach hiring for mobile? That seems like a ___domain where language is important, since it's tied to the ___domain if you plan on native development (which you should). If you're hiring for an iOS position, are you not going to prioritize a candidate with prior iOS experience over one who has only done Android?
It's difficult for me to imagine a scenario where you would have to resort to a former Android dev unless you aren't willing to pay a fair hourly rate or salary, and you're going to bargain for the opportunity to learn in exchange for lower pay.
For this project, we were using Flask, which is a pretty lightweight framework. Even with Rails I wouldn't mind hiring somebody who didn't know it. My teams are closely collaborative and often do a fair bit of pair programming, so I don't mind learning on the job.
As to the mobile question, it would depend on the team composition. If I'm hiring the first mobile developer, then yeah, I'm going to look for somebody with a lot of experience. Probably the second as well. But for the third and after, I wouldn't put it as a requirement. As long as there are people around who can mentor, then I'd rather hire a strong developer with little mobile experience than a not-so-great developer with plenty of mobile experience.
You state that "a good programmer can learn a language quickly". I think most people who have experience with hiring developers disputes this. Learning a language is also one of the easier hurdles to overcome when moving into a new programming ___domain.
If you're hiring for a Ruby on Rails team, and you want to hire someone who has prior experience as a developer but has never touched Ruby in their life, you're probably not going to be too worried about how quickly it will take them to learn Ruby. The real challenge will be learning Rails, and then becoming proficient enough to work alongside the current development team and the pre-existing codebase.
Also, how do you approach hiring for mobile? That seems like a ___domain where language is important, since it's tied to the ___domain if you plan on native development (which you should). If you're hiring for an iOS position, are you not going to prioritize a candidate with prior iOS experience over one who has only done Android?
It's difficult for me to imagine a scenario where you would have to resort to a former Android dev unless you aren't willing to pay a fair hourly rate or salary, and you're going to bargain for the opportunity to learn in exchange for lower pay.