Question

I have a function that executed in c. When a certain condition is met I want to change the state of a UIButton. I was trying to dispatch an NSNotification but that doesnt work.

What would be a good way to send a message to an obj-c object from a c function?

Ideally I would like to somehow be able to use NSNotification

Answer 1

The C Code needs to be inside of a .m file. If it is not then add a C callback function inside your .m that can post your notification or do something else for you. Here is an example of accessing the Objective-C class that calls a C function outside of a .m file.

//SomeCCode.c
void someCFunction(int somevar, void (callback) (void*) , void *context)
{
    doSomething(somevar);
    callback(context);
}

//SomeClass.m
void someCCallbackInObjC(void *context)
{
    SomeClass *myclass = (SomeClass*)context;
    //Access my class or just post notification
}

@implementation SomeClass

...
-(void)someMethod
{
    someCFunction(0, someCCallbackInObjC, self);
}
...

@end