Apple has posted the preliminary version of the iPhone OS 4 Software Development Kit, also known as the iPhone SDK 4 beta, to its Developer Web Site. The SDK download is 2.9GB in size, with separate iPhone OS 4.0 operating system betas at roughly 300MB-400MB a piece.
Apple’s OS betas are for 2008 and 2009 iPhone and iPod touch models only. They notably exclude the iPad, which is explicitly disclaimed as not compatible with “iPhone OS 4.0”, and 2007 iPhone and iPod touch models, which are not and apparently will not be supported by iPhone OS 4.
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