MVC-N Discussion

A discussion about proper networking in your iOS based application

1. Marcus S. Zarra MVC-N
2. MyUIViewController Network Request Network Request OtherUIViewController Network Request Network Request ThirdUIViewController Network Request Network Request Controller Layer FourthUIViewController Network Request Network Request Core Data Anti-Pattern
3. MVCN Network Controller
4. MVCN MyUIViewController OtherUIViewController ThirdUIViewController FourthUIViewController NetworkController NR NR NR NR NR NR Core Data The Net
5. NetworkController NR NR NR NR NR NR Network Controller Dependency Injection Singleton AppDelegate property class NetworkController: NSObject { } let queue = NSOperationQueue() var mainContext: NSManagedObjectContext? func requestMyData() func requestMyData() -> NSFetchedResultsController func requestMyData(completion: (Void) -> Bool)
6. NetworkController NR NR NR NR NR NR Network Controller class MyNetworkRequest: NSOperation { var context: NSManagedObjectContext? init(myParam1: String, myParam2: String) }
7. class MyNetworkRequest: NSOperation { var context: NSManagedObjectContext? private var innerContext: NSManagedObjectContext? private var task: NSURLSessionTask? private let incomingData = NSMutableData() init(myParam1: String, myParam2: String) { super.init() //set some parameters here } var internalFinished: Bool = false override var finished: Bool { get { return internalFinished } set (newAnswer) { willChangeValueForKey("isFinished") internalFinished = newAnswer didChangeValueForKey("isFinished") } } }
8. func URLSession(session: NSURLSession, dataTask: NSURLSessionDataTask, didReceiveResponse response: NSURLResponse, completionHandler: (NSURLSessionResponseDisposition) -> Void) { if cancelled { finished = true sessionTask?.cancel() return } //Check the response code and react appropriately completionHandler(.Allow) } func URLSession(session: NSURLSession, dataTask: NSURLSessionDataTask, didReceiveData data: NSData) { if cancelled { finished = true sessionTask?.cancel() return } incomingData.appendData(data) }
9. func URLSession(session: NSURLSession, task: NSURLSessionTask, didCompleteWithError error: NSError?) { if cancelled { finished = true sessionTask?.cancel() return } if error != nil { self.error = error log("Failed to receive response: \(error)") finished = true return } //PROCESS DATA INTO CORE DATA finished = true }
10. Unit Testing
11. Network Conditions • Operations can report speeds • Control Performance via the Queue • Network Controller can react to conditions • Central location for canceling of actions • Single decision point for background processing
12. Wrap up • Own your network code • Don’t put network code in view controllers • Keep all network code together • All UI should feed from Core Data • Disconnect data collection and data display
13. Marcus S. Zarra marcus@cimgf.com http://www.cimgf.com Thank You