ios – Property ‘notificationRelay’ not discovered on object of sort ‘AppDelegate *

I’m a react-native developer, attempting to combine native iOS library.

Hyperlink to library: https://github.com/uber/startup-reason-reporter

In that they’ve this instruction

// Decide whether or not the app crashed on a previous launch
BOOL crashedOnPriorLaunch = ...

// Initialize a storage mechanism implementing UBApplicationStartupReasonReporterPriorRunInfoProtocol
id<UBApplicationStartupReasonReporterPriorRunInfoProtocol> runInfo = ...

// Initialize the notification relay
id<UBApplicationStartupReasonReporterNotificationRelayProtocol> = [[UBApplicationStartupReasonReporterNotificationRelay alloc] init]

// Initialize the startup motive reporter
UBApplicationStartupReasonReporter *startupReasonReporter = [[UBApplicationStartupReasonReporter alloc] initWithPreviousRunDidCrash:crashedOnPriorLaunch
        previousRunInfo:runInfo
        notificationRelay: notificationRelay
        debugging:[UBBuildType isDebugBuild]];

// Revenue
UBStartupReason startupReason = startupReasonReporter.startupReason

// ...
// In AppDelegate join notification relay to app lifecycle strategies

- (void)applicationDidBecomeActive:(UIApplication *)software
{
    [self.notificationRelay updateApplicationStateNotification:[NSNotification notificationWithName:UIApplicationDidBecomeActiveNotification object:nil]];
}

- (void)applicationWillResignActive:(UIApplication *)software
{
    [self.notificationRelay updateApplicationStateNotification:[NSNotification notificationWithName:UIApplicationWillResignActiveNotification object:nil]];
}

- (void)applicationWillTerminate:(UIApplication *)software
{
    [self.notificationRelay updateApplicationStateNotification:[NSNotification notificationWithName:UIApplicationWillTerminateNotification object:nil]];
}

Once I put this in AppDelegate.m, it says this

   // In AppDelegate join notification relay to app lifecycle strategies
    
    - (void)applicationDidBecomeActive:(UIApplication *)software
    {
        [self.notificationRelay updateApplicationStateNotification:[NSNotification notificationWithName:UIApplicationDidBecomeActiveNotification object:nil]];
    }
    
    - (void)applicationWillResignActive:(UIApplication *)software
    {
        [self.notificationRelay updateApplicationStateNotification:[NSNotification notificationWithName:UIApplicationWillResignActiveNotification object:nil]];
    }
    
    - (void)applicationWillTerminate:(UIApplication *)software
    {
        [self.notificationRelay updateApplicationStateNotification:[NSNotification notificationWithName:UIApplicationWillTerminateNotification object:nil]];
    }

Property ‘notificationRelay’ not discovered on object of sort ‘AppDelegate
*

Any concept why this might be occurring?