Apple Watch: Is this a good way to allow apple watch app to grab new data?

Currently, I am building an apple watch app similar to the mail app. I am sending the API key from my iOS app to my Apple Watch App and using the API key to make requests from my Apple Watch.

This is how I send the API key to my Apple Watch App.

NSDictionary *applicationDict = @{@"apiKey" : apiKey };

if ([WCSession defaultSession].reachable) {
    [[WCSession defaultSession] sendMessage:applicationDict replyHandler:^(NSDictionary *replyHandler) {

    } errorHandler:^(NSError *error) {

    }];
} else {
    [session  updateApplicationContext:applicationDict error:nil];
}

This is how I store the API key in user defaults for my apple watch app. I save the API key. Then, I use the API key to make requests. If the user ever logs out of the iPhone app, I remove the API key in defaults.

 // receive apiKey if watch app is in the foreground
func session(_ session: WCSession, didReceiveApplicationContext applicationContext: [String : Any]) {
    if let apiKeyString = message[@"apiKey"] as? String{
        defaults.set(apiKeyString, forKey:kApiKey)
        syncMail(apiKey: apiKeyString)
    } 
}

// receive apiKey if watch app is in the background
    func session(_ session: WCSession, didReceiveApplicationContext applicationContext: [String : Any]) {
        if let apiKeyString = applicationContext[@"apiKey"] as? String{
            defaults.set(apiKeyString, forKey:kApiKey)
            syncMail(apiKey: apiKeyString)
        } 
    }

This seems to work well for me. However, I am not sure if this is the best way. I was wondering if there is any way I can improve my method? Any tips or suggestions are appreciated.

from Apple Watch: Is this a good way to allow apple watch app to grab new data?