Intercepting phone call - iPhone (correct method to hook in CoreTelephony)

Question

I am new to the jailbreak tweak development scene. I am trying to figure out the appropriate method to 'hook' so I can intercept an incoming call (and then run some code).

I have dumped the header files of CoreTelephony framework however no methods seem obvious to hook. I have tried:

- (void)broadcastCallStateChangesIfNeededWithFailureLogMessage:(id)arg1;
- (BOOL)setUpServerConnection;

but neither have worked. By worked I mean - get called when the iPhone receives a call.

Any pointers as to the appropriate method to hook? Thanks :)

Note: This is going to be a jailbreak tweak using private APIs so it won't be submitted to the App Store.

Answer 1

I didn't test your code, but I think your problem might be that you need to use the Core Telephony notification center to register for that event (not what you had in the code in your comment). Something like this:

// register for all Core Telephony notifications
id ct = CTTelephonyCenterGetDefault();
CTTelephonyCenterAddObserver(ct,   // center
                             NULL, // observer
                             telephonyEventCallback,  // callback
                             NULL,                    // event name (or all)
                             NULL,                    // object
                             CFNotificationSuspensionBehaviorDeliverImmediately);

and your callback function is

static void telephonyEventCallback(CFNotificationCenterRef center, void *observer, CFStringRef name, const void *object, CFDictionaryRef userInfo)
{
    NSString *notifyname = (NSString*)name;
    if ([notifyname isEqualToString:@"kCTCallIdentificationChangeNotification"])
    {
        NSDictionary* info = (NSDictionary*)userInfo;
        CTCall* call = (CTCall*)[info objectForKey:@"kCTCall"];
        NSString* caller = CTCallCopyAddress(NULL, call);

        if (call.callState == CTCallStateDisconnected)
        {
            NSLog(@"Call has been disconnected");
        }
        else if (call.callState == CTCallStateConnected)
        {
            NSLog(@"Call has just been connected");
        }
        else if (call.callState == CTCallStateIncoming)
        {
            NSLog(@"Call is incoming");
        }
        else if (call.callState == CTCallStateDialing)
        {
            NSLog(@"Call is Dialing");
        }
        else
        {
            NSLog(@"None of the conditions");
        }
    }
}

I offer another technique in this similar question here. Also, note my comment in that question about not getting the notifications in a UIApplication that has been put into the background.

Update: see cud_programmer's comment below about using kCTCallStatus on iOS 6 instead of kCTCall.