I have intergrated firebase push notification in my app. I had installed cocoapods fine and do all the code in appdelegate.m file for firebase messaging. Also created certificate and uploaded to firebase to my project, i have followed all the procedure correctly but when i run the app i got some errors and app do not run and shows error while linking. My code for firebase is this,
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
        [FIRApp configure];
        [[NSNotificationCenter defaultCenter]addObserver:self selector:@selector(tokenRefreshCallBack:) name:kFIRInstanceIDTokenRefreshNotification object:nil];
        UIUserNotificationType type=(UIUserNotificationTypeAlert | UIUserNotificationTypeBadge | UIUserNotificationTypeSound);
        UIUserNotificationSettings *settings=[UIUserNotificationSettings settingsForTypes:type categories:nil];
        [application registerUserNotificationSettings:settings];
        [application registerForRemoteNotifications];
        return YES;
    }
    -(void)tokenRefreshCallBack:(NSNotification *)notification{
        NSString *refreshToken=[[FIRInstanceID instanceID]token];
        NSLog(@"Instance IDToken : %@",refreshToken);
        [self connecttoFirebase];
    }
    -(void)connecttoFirebase{
        [[FIRMessaging messaging]connectWithCompletion:^(NSError * _Nullable error){
            if (error !=nil) {
            NSLog(@"Unable to connect to FCM %@",error);
            }else{
            NSLog(@"Connected to FCM");
            }
            }];
    }
    -(void)application:(UIApplication *)application didReceiveRemoteNotification:(nonnull NSDictionary *)userInfo fetchCompletionHandler:(nonnull void (^)(UIBackgroundFetchResult))completionHandler{
        NSLog(@"Message ID : %@",userInfo[@"gcm.message_id"]);
        NSLog(@"%@",userInfo);
    }
 
    