Are blocks supported in iPhone OS 3.1.3?

I am 开发者_如何学Pythontrying to use Objective-C blocks in an iPhone 3.1.3 app but am getting a linkage error:

"_NSConcreteGlobalBlock," referenced from:

Any ideas as to whether blocks are supported in the iPhone 3.1.3 SDK? I found conflicting reports on the internet.

Blocks are not supported natively on the iPhone. However, there is an option: The "plblocks" project allows you to compile block-based code for 10.5 and iPhone OS 2.2+:

• http://code.google.com/p/plblocks/ (project)
• http://github.com/zakovyrya/iPhone-blocks (example of use on iPhone)