I'm in the process of learning iOS, and I'm coming from a web dev background where CSS controls 70-90% of the UI, and Python/C++ desktop dev where there are highly customizable UI toolkits for most things.

I'm trying to figure out how people make good-looking apps without graphic design skills.

You always hear about some 8 year old or 14 year old who made a successful app. So I assume that even if the required code was relatively basic, the app must have looked good if it was a success. But I find it really unlikely that these kids have advanced PhotoShop skills as well as having learned iOS programming at such a young age. Frankly, the same goes for most independent app developers....as they say, unicorns don't exist.

So what's the deal? Can you make a good-looking, market quality app without those skills? What are the limitations?