Cleaner logic in LibraryOnlineTBVC & LibRefreshOp

Kiwix/LibraryOnlineTBVC.swift

@@ -9,11 +9,11 @@
 import UIKit
 import CoreData
 
-class LibraryOnlineTBVC: UITableViewController, NSFetchedResultsControllerDelegate, BookTableCellDelegate, LTBarButtonItemDelegate, RefreshLibraryOperationDelegate, DZNEmptyDataSetSource, DZNEmptyDataSetDelegate {
+class LibraryOnlineTBVC: UITableViewController, NSFetchedResultsControllerDelegate, BookTableCellDelegate, LTBarButtonItemDelegate, DZNEmptyDataSetSource, DZNEmptyDataSetDelegate {
     
     var booksShowingDetail = Set<Book>()
-    weak var refreshOperation: RefreshLibraryOperation?
     var messsageLabelConfigTimer: NSTimer?
+    var refreshing = false
     
     // MARK: - Override
     
@@ -26,18 +26,20 @@ class LibraryOnlineTBVC: UITableViewController, NSFetchedResultsControllerDelega
         tableView.emptyDataSetSource = self
         tableView.emptyDataSetDelegate = self
         
-        reconnectToExistingRefreshOperation()
-        refreshLibraryForTheFirstTime()
         configureToolBar()
     }
     
     override func viewWillAppear(animated: Bool) {
         super.viewWillAppear(animated)
         segmentedControl.selectedSegmentIndex = 0
-        configureRefreshStatus()
         messsageLabelConfigTimer = NSTimer.scheduledTimerWithTimeInterval(60.0, target: self, selector: #selector(configureMessage), userInfo: nil, repeats: true)
     }
     
+    override func viewDidAppear(animated: Bool) {
+        super.viewDidAppear(animated)
+        refreshLibraryForTheFirstTime()
+    }
+    
     override func viewWillDisappear(animated: Bool) {
         super.viewWillDisappear(animated)
         messsageLabelConfigTimer?.invalidate()
@@ -68,38 +70,40 @@ class LibraryOnlineTBVC: UITableViewController, NSFetchedResultsControllerDelega
         startRefresh(invokedAutomatically: false)
     }
     
-    // MARK: - RefreshLibraryOperationDelegate
-    
-    func refreshDidStart() {
-        configureRefreshStatus()
-        configureToolBarVisibility(animated: true)
-    }
-    
-    func refreshDidFinish() {
-        configureRefreshStatus()
-        configureToolBarVisibility(animated: true)
-    }
-    
     // MARK: - Others
     
-    func reconnectToExistingRefreshOperation() {
-        guard let operation = refreshOperation ??
-            UIApplication.globalOperationQueue.operation(String(RefreshLibraryOperation)) as? RefreshLibraryOperation
-            else {return}
-        refreshOperation = operation
-        operation.delegate = self
-    }
-    
     func refreshLibraryForTheFirstTime() {
         guard Preference.libraryLastRefreshTime == nil else {return}
         startRefresh(invokedAutomatically: true)
     }
     
     func startRefresh(invokedAutomatically invokedAutomatically: Bool) {
-        let refreshOperation = RefreshLibraryOperation(invokedAutomatically: invokedAutomatically)
+        let refreshOperation = RefreshLibraryOperation(invokedAutomatically: invokedAutomatically) { (errorCode) in
-        refreshOperation.delegate = self
+            defer {
+                NSOperationQueue.mainQueue().addOperationWithBlock({
+                    self.refreshing = false
+                    self.configureMessage()
+                    self.configureRotatingStatus()
+                    self.configureEmptyTableBackground()
+                })
+            }
+            if let errorCode = errorCode {
+                if errorCode == .NetworkError {
+                    let alertOperation = RefreshLibraryInternetRequiredAlert(presentationContext: self)
+                    UIApplication.appDelegate.globalOperationQueue.addOperation(alertOperation)
+                }
+            } else {
+                guard !Preference.libraryHasShownPreferredLanguagePrompt else {return}
+                let operation = RefreshLibraryLanguageFilterAlert(libraryOnlineTBVC: self)
+                UIApplication.appDelegate.globalOperationQueue.addOperation(operation)
+            }
+        }
+        
+        refreshing = true
+        configureMessage()
+        configureRotatingStatus()
+        configureEmptyTableBackground()
         UIApplication.globalOperationQueue.addOperation(refreshOperation)
-        self.refreshOperation = refreshOperation
     }
     
     // MARK: - ToolBar Button
@@ -126,15 +130,13 @@ class LibraryOnlineTBVC: UITableViewController, NSFetchedResultsControllerDelega
         setToolbarItems(toolBarItems, animated: false)
         
         configureToolBarVisibility(animated: false)
-        configureMessage(isRefreshing: false)
+        configureMessage()
     }
     
-    func configureToolBarVisibility(animated animated: Bool) {
+    func configureMessage() {
-        navigationController?.setToolbarHidden(fetchedResultController.fetchedObjects?.count == 0, animated: animated)
+        if refreshing {
-    }
+            messageButton.text = LocalizedStrings.refreshing
-    
+        } else {
-    func configureMessage(isRefreshing isRefreshing: Bool = false) {
-        if !isRefreshing {
             guard let sectionInfos = fetchedResultController.sections else {messageButton.text = nil; return}
             let count = sectionInfos.reduce(0) {$0 + $1.numberOfObjects}
             let localizedBookCountString = String.localizedStringWithFormat(NSLocalizedString("%d book(s) available for download", comment: "Book Library, online book catalogue message"), count)
@@ -150,15 +152,18 @@ class LibraryOnlineTBVC: UITableViewController, NSFetchedResultsControllerDelega
                 return string
             }()
             messageButton.text = localizedBookCountString + "\n" + localizedRefreshTimeString
-        } else {
-            messageButton.text = LocalizedStrings.refreshing
         }
     }
     
-    func configureRefreshStatus() {
+    func configureToolBarVisibility(animated animated: Bool) {
-        let executing = refreshOperation?.executing ?? false
+        navigationController?.setToolbarHidden(fetchedResultController.fetchedObjects?.count == 0, animated: animated)
-        executing ? refreshLibButton.startRotating() : refreshLibButton.stopRotating()
+    }
-        configureMessage(isRefreshing: executing)
+    
+    func configureRotatingStatus() {
+        refreshing ? refreshLibButton.startRotating() : refreshLibButton.stopRotating()
+    }
+    
+    func configureEmptyTableBackground() {
         tableView.reloadEmptyDataSet()
     }
     
@@ -187,7 +192,7 @@ class LibraryOnlineTBVC: UITableViewController, NSFetchedResultsControllerDelega
     }
     
     func buttonTitleForEmptyDataSet(scrollView: UIScrollView!, forState state: UIControlState) -> NSAttributedString! {
-        if let _ = refreshOperation {
+        if refreshing == true {
             let text = NSLocalizedString("Refreshing...", comment: "Book Library, book downloader, refreshing button text")
             let attributes = [NSFontAttributeName: UIFont.boldSystemFontOfSize(17.0), NSForegroundColorAttributeName: UIColor.darkGrayColor()]
             return NSAttributedString(string: text, attributes: attributes)
@@ -207,7 +212,7 @@ class LibraryOnlineTBVC: UITableViewController, NSFetchedResultsControllerDelega
     }
     
     func emptyDataSetDidTapButton(scrollView: UIScrollView!) {
-        guard self.refreshOperation == nil else {return}
+        guard !refreshing else {return}
         startRefresh(invokedAutomatically: false)
     }
     
@@ -310,7 +315,7 @@ class LibraryOnlineTBVC: UITableViewController, NSFetchedResultsControllerDelega
         fetchedResultController.fetchRequest.predicate = onlineCompoundPredicate
         fetchedResultController.performFetch(deleteCache: true)
         tableView.reloadData()
-        configureMessage(isRefreshing: false)
+        configureMessage()
     }
     
     private var langPredicate: NSPredicate {
@@ -360,5 +365,7 @@ class LibraryOnlineTBVC: UITableViewController, NSFetchedResultsControllerDelega
     
     func controllerDidChangeContent(controller: NSFetchedResultsController) {
         tableView.endUpdates()
+        configureToolBarVisibility(animated: true)
+        configureMessage()
     }
 }

Kiwix/RefreshLibraryOperation.swift

@@ -11,21 +11,20 @@ import CoreData
 
 class RefreshLibraryOperation: GroupOperation {
     
-    weak var delegate: RefreshLibraryOperationDelegate?
+    var completionHandler: ((errorCode: Int?) -> Void)?
-    weak var presentationContext: LibraryOnlineTBVC?
-    var completionHandler: (() -> Void)?
     
-    init(invokedAutomatically: Bool, presentationContext: LibraryOnlineTBVC? = nil, completionHandler: (() -> Void)? = nil) {
+    init(invokedAutomatically: Bool, completionHandler: ((errorCode: Int?) -> Void)?) {
         super.init(operations: [])
         
         name = String(RefreshLibraryOperation)
+        self.completionHandler = completionHandler
         
         // 1.Parse
         let parseOperation = ParseLibraryOperation()
         
         // 0.Download library
         let url = NSURL(string: "http://www.kiwix.org/library.xml")!
-        let task = NSURLSession.sharedSession().dataTaskWithURL(url) { (data, response, error) -> Void in
+        let task = NSURLSession.sharedSession().dataTaskWithURL(url) { [unowned parseOperation] (data, response, error) -> Void in
             if let error = error {self.aggregateError(error)}
             parseOperation.xmlData = data
         }
@@ -33,24 +32,9 @@ class RefreshLibraryOperation: GroupOperation {
         fetchOperation.addObserver(NetworkObserver())
         fetchOperation.addCondition(ReachabilityCondition(host: url, allowCellular: Preference.libraryRefreshAllowCellularData))
         
-        let stateObserver = BlockObserver(
-            startHandler: { (operation) -> Void in
-                NSOperationQueue.mainQueue().addOperationWithBlock({ () -> Void in
-                    self.delegate?.refreshDidStart()
-                })
-            },
-            produceHandler: nil) { (operation, errors) -> Void in
-                NSOperationQueue.mainQueue().addOperationWithBlock({ () -> Void in
-                    self.delegate?.refreshDidFinish()
-                })
-        }
-        addObserver(stateObserver)
-        
-        addCondition(MutuallyExclusive<RefreshLibraryOperation>())
         if invokedAutomatically {
             addCondition(AllowAutoRefreshCondition())
             addCondition(LibraryIsOldCondition())
-            addCondition(ReachabilityCondition(host: url, allowCellular: Preference.libraryRefreshAllowCellularData))
         }
         
         addOperation(fetchOperation)
@@ -59,22 +43,10 @@ class RefreshLibraryOperation: GroupOperation {
     }
     
     override func finished(errors: [NSError]) {
-        if let firstError = errors.first {
+        completionHandler?(errorCode: errors.first?.code)
-            if firstError.code == .NetworkError {
-                produceOperation(RefreshLibraryInternetRequiredAlert(presentationContext: presentationContext))
-            }
-        } else {
-            guard !Preference.libraryHasShownPreferredLanguagePrompt else {return}
-            produceOperation(RefreshLibraryLanguageFilterAlert(libraryOnlineTBVC: presentationContext))
-        }
     }
 }
 
-protocol RefreshLibraryOperationDelegate: class {
-    func refreshDidStart()
-    func refreshDidFinish()
-}
-
 class ParseLibraryOperation: Operation, NSXMLParserDelegate {
     var xmlData: NSData?
     let context: NSManagedObjectContext
@@ -91,7 +63,7 @@ class ParseLibraryOperation: Operation, NSXMLParserDelegate {
     }
     
     override func execute() {
-        guard let data = xmlData else {return}
+        guard let data = xmlData else {finish(); return}
         let xmlParser = NSXMLParser(data: data)
         xmlParser.delegate = self
         xmlParser.parse()
@@ -106,7 +78,7 @@ class ParseLibraryOperation: Operation, NSXMLParserDelegate {
         }
     }
     
-    @objc internal func parser(parser: NSXMLParser, didStartElement elementName: String, namespaceURI: String?, qualifiedName qName: String?, var attributes attributeDict: [String : String]) {
+    @objc internal func parser(parser: NSXMLParser, didStartElement elementName: String, namespaceURI: String?, qualifiedName qName: String?, attributes attributeDict: [String : String]) {
         guard elementName == "book" else {return}
         guard let id = attributeDict["id"] else {return}