Readmersion: Chinese - Read, Listen, Write, Speak & Understand Mandarin by Nathan Cain

Simplified Chinese reader with a few twists; including audio lessons to practice your listening and speaking.
Basically it goes like this: You paste in any Chinese article or story you want. The app will display it with all the pinyin (pronunciation guide) above. Then as you read along you tap all the words you don't know so you get shown the definition(s).
Here is the twist: when you tap a word you have already looked up before, the app doesn't show you the definition right away, but instead shows you the sentence(s) you have seen that word in before. This will allow you to try to remember what that word means while staying completely immersed in Chinese.
The app will be keeping track of your progress with each word. After you have recognized the word a few times without looking it up, then the pinyin will no longer be displayed for that word in subsequent paragraphs or articles. So eventually you will be weaned off of the pinyin completely.
There are also customized audio lessons similar in style to PIMSLEUR®. The lessons will help you remember the words you have been reading and having trouble with.
Future features:
"No pinyin" mode.
When you know enough characters the app will start showing you definitions in Chinese, but only if that definition is deemed simple enough for you to understand.
Also, the app's user interface will start slowly turning all Chinese as you learn more and more words. So eventually you will be learning Chinese in Chinese, with no more English.