Syntle is a simple iOS application which helps you memorize the syntax of a new programming language using spaced repetition and flashcards featuring code snippets. At the moment it targets Objective-C programmers who would like to quickly learn the syntax of Swift. There is a quiz after every 5 flashcards.
Next version will support flashcards to learn git and shell scripting.
Here are the links:
PS: What do you think about this app? Please, leave feedback :)