I started to learn PHP about four months ago, and I have been writing some applications for three months. Recently, I've been using CodeIgniter for various projects. Using CodeIgniter is awesome as it is easy to code with, and I don't care about security while using it. I do think though that using a framework may be bad for my background PHP knowledge, because with CodeIgniter I use absolutely different programming methods than when I code normally. I want to ask you which is better; using a framework, or not using a framework?
One of the fundamentals of programming is "don't reinvent the wheel." If a framework has code that you would otherwise implement yourself, by all means use it so that you can focus on your application as a whole. However if you don't like the implementation, then you put your php knowledge to work and flesh out your own alternative.
That said, if you're just studying php to learn the ins and outs, you shouldn't use a framework, but you may benefit from reading its code.