React-Native Zendesk Auth integration - objective-c

Question

I am trying to integrate zendesk with react-native. The problem is that I don't know objective-c so I am having problem with the authentication.
I want to open ZenDeskChat, for that I can do it in 2 different way (anonymous or auth). To use the auth procedure I have to create a JWT from my server and send this token to zendesk before I open the chat. I copy some function from zendesk documentation but because my lake of knowladge with objective-c I can't figure out how to pass the token to zendesk.
I don't know how to use this code.
#implementation ZDKAuthJWT
​
- (void)getToken:(void (^)(NSString * _Nullable, NSError * _Nullable))completion {
// Call completion block once you get the JWT token
completion(<"token">, <"error">);
}
I am supposed to call it somewhere here :
RCT_EXPORT_METHOD(setUserIdentity: (NSDictionary *)user) {
if (user[#"token"]) {
id<ZDKObjCIdentity> userIdentity = [[ZDKObjCJwt alloc] initWithToken:user[#"token"]];
[[ZDKZendesk instance] setIdentity:userIdentity];
RCTAuthJWT *authenticator = [RCTAuthJWT new];
[ZDKChat.instance setIdentityWithAuthenticator:authenticator];
} else {
id<ZDKObjCIdentity> userIdentity = [[ZDKObjCAnonymous alloc] initWithName:user[#"name"] // name is nullable
email:user[#"email"]]; // email is nullable
[[ZDKZendesk instance] setIdentity:userIdentity];
}
}