iOS - 确定Accelerate.framework是否在运行时可用

Question

Is there any way to determine whether the Accelerate.framework is available at runtime from straight C or C++ files?

The examples I've found for conditional coding all seem to require Objective-C introspection (eg, respondsToSelector ) and/or Objective-C apis (eg, UIDevice's systemVersion member)

Answer 1

The usual trick for this is that you weak link against the framework and then check a function pointer exported by that framework for the actual availability. If the framework failed to link because it is not available then the function will be NULL .

So for Accelerate.framework you would do something like this:

#include <Accelerate/Accelerate.h>

if (cblas_sdsdot) {
    NSLog(@"Yay we got Accelerate.framework");
} else {
    NSLog(@"Oh no, no Accelerate.framework");
}

This is described in TN2064 - Ensuring Binary Backwards Compatibility