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What is the easiest way to add an immediate one-time task to a CFRunLoop from a C/C++ program, that is, a callback which must be invoked by the run-loop before it blocks again.

According to the documentation, we have CFRunLoopPerformBlock(), but the problem with it, is that it uses the block-notation which requires Objective-C compilation mode.

Is there something similar to CFRunLoopPerformBlock() which is available to a C/C++ program, or am I forced to use a zero-delay timer?

Kristian Spangsege
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1 Answers1

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The block language feature does not require the use of Objective-C. It's also supported in C and C++ by Clang. So, you can go ahead and use CFRunLoopPerformBlock().

If you're still looking for alternatives and you wish to target the main thread's run loop (i.e. the main run loop), you can use dispatch_async_f(). Although it's most common to use the block-based functions when using GCD, the functions with the _f suffix take function pointers.

static void my_task_function(void *context)
{
    // ...
}

...

dispatch_async_f(dispatch_get_main_queue(), any_pointer_you_like, my_task_function);
Ken Thomases
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  • Cool, I just discovered the same thing, namely that blocks are available in C too: https://developer.apple.com/library/ios/documentation/Cocoa/Conceptual/Blocks/Articles/bxGettingStarted.html. – Kristian Spangsege Jan 07 '15 at 00:31