I built an iPhone app for reading real books in a language you're learning. Before each chapter, it estimates which words in it you probably don't know yet and teaches them in the sentences where they appear. Then you read the chapter. You can tap any word for its meaning in that sentence.

The books are public-domain classics (Grimms Märchen, Les Malheurs de Sophie, Marianela, Alice im Wunderland), some in a modern version with outdated words replaced. A short reading check at the start estimates your vocabulary, and lessons leave out the words you already know.

It's a free TestFlight beta: https://testflight.apple.com/join/RffWpmxn. I'd like to hear if it seems useful for you and what you miss or did not work for you.