Recommended for Learning Swift / iOS Dev

I am interested in learning Swift / iOS development for iPhone and iPad app development. I purchased the iOS Apprentice book and would like to know the recommended path that will help me to learn the skills necessary to be a successful app developer.

Thanks.

Work through the book, make the apps detailed within. Come up with ideas for making your own apps, or find someone with ideas willing to pay you to make them. Make apps, finish what you start, and publish. Keep learning, keep making.

It’s a bit of a glib answer, but I don’t know what you’re looking for or how you’d define ‘successful’.