What programming languages can one use to develop iPhone, iPod Touch and iPad (iOS) applications?

Question

What programming languages can one use to develop iPhone, iPod Touch and iPad (iOS) applications?

Also are there plans in the future to expand the amount of programm

Answer 1

The SDK agreement and App store guidelines have been changed (circa Sept 2010).

You can now probably use any compiled language that will compile to the same static ARM object file format as Xcode produces and that will link to (only) the public API's within Apple's frameworks and libraries. However, you can not use a JIT compiled language unless you pre-compile all object code before submission to Apple for review.

You can use any interpreted language, as long as you embed the interpreter, and do not allow the interpreter or the app to download and run any interpretable code other than code built into the app bundle before submission to Apple for review, or source code typed-in by the user.

Objective C and C will likely still be the most optimal programming language for anything requiring high performance and the latest API support (* see update below), as those are the languages for which Apple targets its iOS frameworks and tunes its ARM processor chipsets. Apple also supports the use of Javascript/HTML5 inside a UIWebView. Those are the only languages for which Apple has announced support. Anything else you will have to find support elsewhere.

But, if you really want, there are at least a half dozen BASIC interpreters now available in the iOS App store, so even "Stone Age" programming methodology is now allowed.

Added: (*) As of late 2014, one can also develop apps using Apple's new Swift programming language. As of early 2015, submitted binaries must include 64-bit (arm64) support.