Which user agent should I use for my own web browser?

I'm currently using this one:

#define CUSTOM_USER_AGENT_IPHONE = "Mozilla/5.0 (iPhone; CPU iPhone OS 10_3_2 like Mac OS X) AppleWebKit/603.1.30 (KHTML, like Gecko) Mobile/14F89 Safari/602.1"

Which I think is outdated. How should I go about updating this? Should I submit a newer version of my web browser app to the App Store whenever the user agent has changed to something newer?

webView.customUserAgent = self.customUserAgent;

- (NSString *)customUserAgent {
    
    // Checking interface idiom for the appropriate user agent string.
    
    if ([[UIDevice currentDevice] userInterfaceIdiom] == UIUserInterfaceIdiomPhone) {
        
        return @CUSTOM_USER_AGENT_IPHONE;
    }
    else {
        
        return @CUSTOM_USER_AGENT_IPAD;
    }
}