Move background handling into Feed.swift for better state control

Classes/Issues/IssuesViewController.swift

@@ -505,7 +505,7 @@ final class IssuesViewController:
             emptyView.delegate = self
             emptyView.button.isHidden = false
             return emptyView
-        case .loading, .loadingNext:
+        case .loading, .loadingNext, .initial:
             return nil
         }
     }

Classes/Notifications/NotificationsViewController.swift

@@ -13,14 +13,11 @@ import Squawk
 
 final class NotificationsViewController: BaseListViewController2<Int>,
 BaseListViewController2DataSource,
-ForegroundHandlerDelegate,
 FlatCacheListener,
 TabNavRootViewControllerType,
-BaseListViewController2EmptyDataSource
-{
+BaseListViewController2EmptyDataSource {
 
     private let modelController: NotificationModelController
-    private let foreground = ForegroundHandler(threshold: 5 * 60)
     private let inboxType: InboxType
     private var notificationIDs = [String]()
 
@@ -32,11 +29,13 @@ BaseListViewController2EmptyDataSource
         self.modelController = modelController
         self.inboxType = inboxType
 
-        super.init(emptyErrorMessage: NSLocalizedString("Cannot load your inbox.", comment: ""))
+        super.init(
+            emptyErrorMessage: NSLocalizedString("Cannot load your inbox.", comment: ""),
+            backgroundThreshold: 5 * 60
+        )
 
         self.dataSource = self
         self.emptyDataSource = self
-        self.foreground.delegate = self
 
         switch inboxType {
         case .all: title = NSLocalizedString("All", comment: "")
@@ -283,12 +282,6 @@ BaseListViewController2EmptyDataSource
         })
     }
 
-    // MARK: ForegroundHandlerDelegate
-
-    func didForeground(handler: ForegroundHandler) {
-        feed.refreshHead()
-    }
-
     // MARK: FlatCacheListener
 
     func flatCacheDidUpdate(cache: FlatCache, update: FlatCache.Update) {

Classes/PullRequestReviews/PullRequestReviewCommentsViewController.swift

@@ -173,7 +173,7 @@ final class PullRequestReviewCommentsViewController: MessageViewController,
             emptyView.delegate = self
             emptyView.button.isHidden = false
             return emptyView
-        case .loadingNext:
+        case .loadingNext, .initial:
             return nil
         case .loading:
             return EmptyLoadingView()

Classes/Systems/Feed.swift

@@ -17,6 +17,7 @@ protocol FeedDelegate: class {
 final class Feed: NSObject, UIScrollViewDelegate {
 
     enum Status {
+        case initial
         case idle
         case loading
         case loadingNext
@@ -25,31 +26,54 @@ final class Feed: NSObject, UIScrollViewDelegate {
     let swiftAdapter: ListSwiftAdapter
     let collectionView: UICollectionView
 
-    public private(set) var status: Status = .idle
+    public private(set) var status: Status = .initial
     private weak var delegate: FeedDelegate?
     private let feedRefresh = FeedRefresh()
     private let managesLayout: Bool
     private let loadingView = EmptyLoadingView()
 
+    private let backgroundThreshold: CFTimeInterval?
+    private var backgroundTime: CFTimeInterval?
+
     init(
         viewController: UIViewController,
         delegate: FeedDelegate,
         collectionView: UICollectionView? = nil,
-        managesLayout: Bool = true
+        managesLayout: Bool = true,
+        backgroundThreshold: CFTimeInterval? = nil
         ) {
         self.swiftAdapter = ListSwiftAdapter(viewController: viewController)
         self.delegate = delegate
         self.managesLayout = managesLayout
         self.collectionView = collectionView
             ?? UICollectionView(frame: .zero, collectionViewLayout: ListCollectionViewLayout.basic())
+        self.backgroundThreshold = backgroundThreshold
+
         super.init()
+
         self.adapter.scrollViewDelegate = self
 
         self.collectionView.alwaysBounceVertical = true
         self.collectionView.backgroundColor = Styles.Colors.background
         self.collectionView.refreshControl = feedRefresh.refreshControl
         self.collectionView.keyboardDismissMode = .onDrag
         feedRefresh.refreshControl.addTarget(self, action: #selector(Feed.onRefresh(sender:)), for: .valueChanged)
+
+        if backgroundThreshold != nil {
+            let center = NotificationCenter.default
+            center.addObserver(
+                self,
+                selector: #selector(didBecomeActive),
+                name: .UIApplicationDidBecomeActive,
+                object: nil
+            )
+            center.addObserver(
+                self,
+                selector: #selector(willResignActive),
+                name: .UIApplicationWillResignActive,
+                object: nil
+            )
+        }
     }
 
     // MARK: Public API
@@ -122,7 +146,7 @@ final class Feed: NSObject, UIScrollViewDelegate {
     // MARK: Private API
 
     private func refresh() {
-        guard status == .idle else { return }
+        guard status == .idle || status == .initial else { return }
         status = .loading
         delegate?.loadFromNetwork(feed: self)
     }
@@ -150,4 +174,37 @@ final class Feed: NSObject, UIScrollViewDelegate {
         }
     }
 
+    // MARK: Notifications
+
+    @objc func willResignActive() {
+        backgroundTime = CACurrentMediaTime()
+    }
+
+    @objc func didBecomeActive() {
+        defer { backgroundTime = nil }
+
+        let refresh: (Bool) -> Void = { head in
+            // there seems to be a bug where refreshing while still becoming active messes up the iOS 11 header and
+            // refresh control. put an artificial delay to let the system cool down?
+            DispatchQueue.main.asyncAfter(deadline: .now() + 0.3, execute: {
+                if head {
+                    self.refreshHead()
+                } else {
+                    self.refresh()
+                }
+            })
+        }
+
+        // if foreground and haven't done an initial load, refresh
+        // can occur when process is still alive after a background fetch
+        if status == .initial {
+            // dont refresh head since spinner will still be shown
+            refresh(false)
+        } else if let backgroundTime = self.backgroundTime,
+            let backgroundThreshold = self.backgroundThreshold,
+            CACurrentMediaTime() - backgroundTime > backgroundThreshold {
+            refresh(true)
+        }
+    }
+
 }

Classes/View Controllers/BaseListViewController2.swift

@@ -25,16 +25,22 @@ ListSwiftAdapterEmptyViewSource,
 EmptyViewDelegate {
 
     private let emptyErrorMessage: String
+    private let backgroundThreshold: CFTimeInterval?
 
     public weak var dataSource: BaseListViewController2DataSource?
     public weak var emptyDataSource: BaseListViewController2EmptyDataSource?
 
-    public private(set) lazy var feed: Feed = { Feed(viewController: self, delegate: self) }()
+    public private(set) lazy var feed: Feed = { Feed(
+        viewController: self,
+        delegate: self,
+        backgroundThreshold: backgroundThreshold
+        ) }()
     private var page: PageType?
     private var hasError = false
 
-    init(emptyErrorMessage: String) {
+    init(emptyErrorMessage: String, backgroundThreshold: CFTimeInterval? = nil) {
         self.emptyErrorMessage = emptyErrorMessage
+        self.backgroundThreshold = backgroundThreshold
         super.init(nibName: nil, bundle: nil)
     }
 

Freetime.xcodeproj/project.pbxproj

@@ -383,7 +383,6 @@
 		29DB264A1FCA10A800C3D0C9 /* GithubHighlighting.swift in Sources */ = {isa = PBXBuildFile; fileRef = 29DB26491FCA10A800C3D0C9 /* GithubHighlighting.swift */; };
 		29DB5D152132227F00E408D9 /* InboxZeroLoader.swift in Sources */ = {isa = PBXBuildFile; fileRef = 29DB5D142132227F00E408D9 /* InboxZeroLoader.swift */; };
 		29DB5D192133418300E408D9 /* LocalNotificationsCache.swift in Sources */ = {isa = PBXBuildFile; fileRef = 29DB5D182133418200E408D9 /* LocalNotificationsCache.swift */; };
-		29EB1EEF1F425E5100A200B4 /* ForegroundHandler.swift in Sources */ = {isa = PBXBuildFile; fileRef = 29EB1EEE1F425E5100A200B4 /* ForegroundHandler.swift */; };
 		29EDFE7C1F65C580005BCCEB /* SplitViewTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 29EDFE7B1F65C580005BCCEB /* SplitViewTests.swift */; };
 		29EDFE821F661562005BCCEB /* RepositoryReadmeModel.swift in Sources */ = {isa = PBXBuildFile; fileRef = 29EDFE811F661562005BCCEB /* RepositoryReadmeModel.swift */; };
 		29EDFE841F661776005BCCEB /* RepositoryReadmeSectionController.swift in Sources */ = {isa = PBXBuildFile; fileRef = 29EDFE831F661776005BCCEB /* RepositoryReadmeSectionController.swift */; };
@@ -926,7 +925,6 @@
 		29DB26491FCA10A800C3D0C9 /* GithubHighlighting.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = GithubHighlighting.swift; sourceTree = "<group>"; };
 		29DB5D142132227F00E408D9 /* InboxZeroLoader.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = InboxZeroLoader.swift; sourceTree = "<group>"; };
 		29DB5D182133418200E408D9 /* LocalNotificationsCache.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = LocalNotificationsCache.swift; sourceTree = "<group>"; };
-		29EB1EEE1F425E5100A200B4 /* ForegroundHandler.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = ForegroundHandler.swift; sourceTree = "<group>"; };
 		29EDFE7B1F65C580005BCCEB /* SplitViewTests.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = SplitViewTests.swift; sourceTree = "<group>"; };
 		29EDFE811F661562005BCCEB /* RepositoryReadmeModel.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = RepositoryReadmeModel.swift; sourceTree = "<group>"; };
 		29EDFE831F661776005BCCEB /* RepositoryReadmeSectionController.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = RepositoryReadmeSectionController.swift; sourceTree = "<group>"; };
@@ -1601,7 +1599,6 @@
 				297AE84E1EC0D58A00B44A1F /* Info.plist */,
 				DC60C6D41F983DF800241271 /* IssueLabelCellTests.swift */,
 				29A476B11ED24D99005D0953 /* IssueTests.swift */,
-				BDB6AA752165B8EA009BB73C /* SwitchBranches.swift */,
 				29C2950D1EC7B43B00D46CD2 /* ListKitTestCase.swift */,
 				29C295091EC7AFA500D46CD2 /* ListTestKit.swift */,
 				2977D8BE215AE12D0073F737 /* LocalNotificationCacheTests.swift */,
@@ -1615,6 +1612,7 @@
 				DC60C6D21F983BB900241271 /* SignatureTests.swift */,
 				45A9D0381F9D3D6A00FD5AEF /* Snapshot Tests */,
 				29EDFE7B1F65C580005BCCEB /* SplitViewTests.swift */,
+				BDB6AA752165B8EA009BB73C /* SwitchBranches.swift */,
 				295F52A61EF1B9D2000B53CF /* Test.md */,
 			);
 			path = FreetimeTests;
@@ -1694,7 +1692,6 @@
 				DC78570F1F97F546009BADDA /* Debouncer.swift */,
 				29C167791ECA14F700439D62 /* Feed.swift */,
 				54AD5E8D1F24D953004A4BD6 /* FeedSelectionProviding.swift */,
-				29EB1EEE1F425E5100A200B4 /* ForegroundHandler.swift */,
 				29C167731ECA0DBB00439D62 /* GithubAPIDateFormatter.swift */,
 				29C0E7061ECBC6C50051D756 /* GithubClient.swift */,
 				2981A8A31EFE9FC700E25EF1 /* GithubEmoji.swift */,
@@ -2787,7 +2784,6 @@
 				291929421F3EA8CD0012067B /* File.swift in Sources */,
 				299E86491EFD9DBB00E5FE70 /* FlexController.m in Sources */,
 				29F3A18620CBF99E00645CB7 /* NotificationModelController.swift in Sources */,
-				29EB1EEF1F425E5100A200B4 /* ForegroundHandler.swift in Sources */,
 				29C167741ECA0DBB00439D62 /* GithubAPIDateFormatter.swift in Sources */,
 				290CA770216AE91300DE04F8 /* UITabBarController+SelectType.swift in Sources */,
 				294434E11FB1F2DA00050C06 /* BookmarkNavigationController.swift in Sources */,