Create a reloading system with ReactiveCocoa

SignalProducerReloaderType

//
//  SignalProducerReloaderType.swift
//  Buienradar
//
//  Created by Antoine van der Lee on 07/03/16.
//  Copyright © 2016 Triple. All rights reserved.
//

import ReactiveCocoa
import CocoaLumberjack

typealias SignalProducerReloaderTypeReloadActionBlock = (() -> Void)

protocol SignalProducerReloaderType {
    var reloadAction:SignalProducerReloaderTypeReloadActionBlock? { get set }
    func signalProducerStarted()
    func signalProducerCompleted()
}

/// Make methods optional
extension SignalProducerReloaderType {
    func signalProducerStarted(){}
    func signalProducerCompleted(){}
}

extension SignalProducerType {
    func attachToSignalProducerReloader(reloader:SignalProducerReloaderType, reloadAction: SignalProducerReloaderTypeReloadActionBlock) -> SignalProducer<Value, Error> {
        var reloader = reloader
        let newProducer = producer.onStarted {
            reloader.signalProducerStarted()
        }.onCompleted {
            reloader.signalProducerCompleted()
        }
        
        reloader.reloadAction = reloadAction
        
        return newProducer
    }
}

final class ForegroundReloader : SignalProducerReloaderType {
    /// Used to check if view is vissible
    var active: Bool = true // default = true

    var reloadAction:SignalProducerReloaderTypeReloadActionBlock?
    
    private let secondsInterval:NSTimeInterval
    private var startDate:NSDate?
    private let logLevel:DDLogLevel = .Warning
    
    /**
     Reloads the attached signal producer after a given period passed
     
     - Parameter secondsInterval: the time to be passed when a new reload should be triggered
     */
    init(secondsInterval:NSTimeInterval){
        DDLogInfo("Init foreground reloader!", level: logLevel)
        self.secondsInterval = secondsInterval
        NSNotificationCenter.defaultCenter().addObserver(self, selector: #selector(ForegroundReloader.onForeground), name: UIApplicationDidBecomeActiveNotification, object: nil)
    }
    
    deinit {
        DDLogInfo("Deinit foreground reloader!", level: logLevel)
        NSNotificationCenter.defaultCenter().removeObserver(self)
    }
    
    @objc private func onForeground(){
        guard let reloadAction = reloadAction where active else { return }
        guard let startDate = startDate where NSDate().timeIntervalSinceDate(startDate) > secondsInterval else {
            DDLogInfo("Wont reload, not enough time passed!", level: logLevel)
            return
        }
        DDLogInfo("Reloading from background!", level: logLevel)
        reloadAction()
    }
    
    func signalProducerStarted(){
        startDate = NSDate()
    }
    
    func reset(){
        reloadAction = nil
    }
}