Hi I use the following code and pass the abid and I am able to send a message to users who have WhatsApp installed but how do I know before I send a message that the user has WhatsApp setup? I don't want to enable the option if it will not work for a specific user.
[[UIApplication sharedApplication] openURL: [NSURL URLWithString:[NSString stringWithFormat:@"whatsapp://send?abid=%d&text=%@", abid, @""]]];
No you can't.
ABAdressBook is not associated with WhatsApp, and the openURL thing only launches WhatsApp if installed (didn't check the target contacts have WhatsApp account or not. WhatsApp does not provide API to check whether the number has registered an account or not.