Not all programming languages have an easy syntax to learn but once you learn the fundamentals of coding in one language, switching to another similar language is much easier. These 5 programming language reference apps for iPhone can help:
PHP Pro Quick Guide: this app helps you learn PHP in a shorter time. It covers syntax, variables, strings, operators, loops, functions, and everything in between.
DataCamp: gets you familiar with fundamentals of R, Python, SQL, and technologies you need to know to become a data scientist. You get bite-sized lessons and learn by writing real code.
Have you found better quick-reference programming apps for iPhone? Please share them here.