Config.swift

import Foundation
import FirebaseRemoteConfig

final class Config {
    
    /// The shared instance of config to use
    static let shared: Config = Config()
    
    /// The maximum number of items that are allowed in this mystery app
    internal let maxItemCount: Int
    
    /// The initalizer is private as intended use is via the shared static property.
    private init() {
        
        // 1. Configure for dev mode if we need it, otherwise a 1 hour expiration duration
        let remoteConfig = FIRRemoteConfig.remoteConfig()
        #if DEBUG
            let expirationDuration: TimeInterval = 0
            remoteConfig.configSettings = FIRRemoteConfigSettings(developerModeEnabled: true)!
        #else
            let expirationDuration: TimeInterval = 3600
        #endif
        
        // 2. Set our default values and keys
        remoteConfig.setDefaults([
            "maximum_item_count": 42 as NSNumber
        ])
        
        // 3. Activate any fetched values before we read anything back
        remoteConfig.activateFetched()
        
        // 4. Now set the properties on config based on what we have currently
        self.maxItemCount = remoteConfig["maximum_item_count"].numberValue!.intValue
        
        // 5. Perform the next fetch so that it's ready when we re-launch
        remoteConfig.fetch(withExpirationDuration: expirationDuration) { status, _ in
            print("[Config] Fetch completed with status:", status, "(\(status.rawValue))")
        }
    }
}