I like learning new things a lot and it is one of the most important aspect in programming.
There are quite a few things about learning which is hard to cover on one post.
I like to write few things about my favourite way to learn new things.(new api, framework, platform or whatever):
The best wat for me learn new things is by teaching someone. However it is not very good to teach things to real people you have zero knowledge about(for example when you learn new library and you have spent just few hours reading documentation).
So what worked for me is to imagine that I am explaining things to someone. Key is imagination. Normally I would go line by line explaining what each line does, how each method works.

After that normally you know what every line of code is doing, since you are not skipping anything.

And you have deep understanding what creators of framework wanted to implement.