Callback methods from C to Objective-C

Question

I have an Objective-C class. What I am doing is I am calling C functions in my objective-C class [ This C functions I implemented in one file , which is part in this sample ios

Answer 1

You can use blocks. Blocks are available to pure C and C++, a block is also always an Objective-C object.

C++ Blocks Objects

Answer 2

First of all Thanks to Ricardo Kloth , Now it's working for me.

Here is my code ...

Objective-C Code:

static id staticObject = nil;

@Implementation MyObjCclass

init
{
    ....

    staticObject = self;
}

// C fun
void functionPointer() 
{ 
    [staticObject message]; // it's working 
}

-(void) message
{

}

@end

Answer 3

even in Blocks also you can't access instance variables right. Please check the following code snippet.

// this is simple block code

NSString* (^trimTheStr)(NSString*) = ^(NSString *str) {

[self myInstanceMethods]; // This will show error right 

NSString *result = nil;

result = [str stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceCharacterSet]];

return result;

};

Answer 4

I ran into this problem aswell. I assume you are using PJSIP for your VoIP app.

What you want to do is create a pointer to the Objective-C class you'd like to send messages to. You already figured you cannot call Objective-C functions from your C callback.

static YourObjCClass *objCClassPtr

@property (nonatomic, retain) YourObjCClass *class

When initializing said class, have the static pointer point to the Objective C object's pointer. (pointer to pointer to object)

objCClassPtr = class;

You are now able to send messages to the Objective-C object using [objCClassPtr message] from your C function as if you would write [class message]

You can point to self the same way.