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It should come as no surprise that Apple is not at all interested in making it easy or simple to port apps between the iPhone OS and other platforms. Doing so would only water down the advantages of the iPhone OS and encourage developers to aim at a lowest common denominator that worked across platforms rather than aspiring to take full advantage of the unique features of the iPhone OS.

This is the same reason why Apple has no interest in supporting Flash or Java as a meta-platform on the iPhone, and also why the company does not want to support third party efforts to create development tools that output iPhone apps. The Flash Professional strategy Adobe hoped to roll out will not offer its users the ability to support iPhone 4.0's multitasking features, Adobe would not be able to rapidly add these features as soon as Apple would like, nor would it necessarily even be in Adobe's interest to add them.

Apple's new prohibition of iPhone 4.0 development in languages other than C, C++ and Objective-C was largely seen as an attack on external development tools like Adobe's Flash CS5. However, observers including Rainer Brockerhoff have since noted that Apple's focus on C languages likely has more to do with the company strategy for optimizing iPhone OS development using Clang.

Clang (short for "C Language") is an open source project Apple funded to serve as a new front end compiler for (unsurprisingly) C, C++ and Objective-C code. Clang connects to LLVM, the Low Level Virtual Machine, which serves as the back end compiler for Apple's Xcode development tool for both Mac OS X and iPhone OS.

The combination of Clang and LLVM effectively replaces GCC (GNU Compiler Collection, the GPL-licensed compiler for Unix-like operating systems). Because Apple's replacement compiler tool chain is licensed under the more permissive BSD license, Apple can integrate it more closely into its Xcode Integrated Development Environment.

Additionally, Clang and LLVM enable Apple to better optimize various steps of the code compiling workflow, creating Mac and iPhone apps that are more efficient, faster, more compact, and easier to debug, due to a variety of optimizations and enhancements that the flexible, modular new compiling tools provide over GCC.

Having invested so much strategic work into Clang and LLVM, it's no wonder Apple is working to push developers to use its own development tools rather than trying to leverage emerging lowest common denominator platforms to deliver iPhone apps that aren't optimized for the iPhone or the latest features of the iPhone OS, including new support for multitasking.