Merge pull request #19539 from wordpress-mobile/tonyli-remove-context-object-reader

Remove the stored context object in `ReaderStreamViewController`

Author: crazytonyli

RELEASE-NOTES.txt

@@ -1,5 +1,6 @@
 21.2
 -----
+* [*] [internal] Refactored fetching posts in the Reader tab. [#19539]
 
 
 21.1

WordPress/Classes/ViewRelated/Reader/ReaderStreamViewController.swift

@@ -58,18 +58,13 @@ import Combine
         }
     }
 
-    lazy var syncContext: NSManagedObjectContext = {
-        return ContextManager.sharedInstance().newDerivedContext()
-    }()
-
-    lazy var service: ReaderPostService = {
-        return ReaderPostService(managedObjectContext: syncContext)
-    }()
+    private var coreDataStack: CoreDataStack {
+        ContextManager.shared
+    }
 
-    /// An alias for the apps's main context – temporarily replaces  `newMainContextChildContext` until we have `NSPersistentContainer` support
-    ///
+    /// An alias for the apps's main context
     private var viewContext: NSManagedObjectContext {
-        ContextManager.sharedInstance().mainContext
+        coreDataStack.mainContext
     }
 
     private(set) lazy var footerView: PostListFooterView = {
@@ -1016,46 +1011,47 @@ import Combine
             return
         }
 
-        syncContext.perform { [weak self] in
-            guard let topicInContext = (try? self?.syncContext.existingObject(with: topic.objectID)) as? ReaderAbstractTopic else {
-                DDLogError("Error: Could not retrieve an existing topic via its objectID")
-                return
-            }
-
-            let objectID = topicInContext.objectID
+        let objectID = topic.objectID
 
-            let successBlock = { [weak self] (count: Int, hasMore: Bool) in
-                DispatchQueue.main.async {
-                    if let strongSelf = self {
-                        if strongSelf.recentlyBlockedSitePostObjectIDs.count > 0 {
-                            strongSelf.recentlyBlockedSitePostObjectIDs.removeAllObjects()
-                            strongSelf.updateAndPerformFetchRequest()
-                        }
-                        strongSelf.updateLastSyncedForTopic(objectID)
+        let successBlock = { [weak self] (count: Int, hasMore: Bool) in
+            DispatchQueue.main.async {
+                if let strongSelf = self {
+                    if strongSelf.recentlyBlockedSitePostObjectIDs.count > 0 {
+                        strongSelf.recentlyBlockedSitePostObjectIDs.removeAllObjects()
+                        strongSelf.updateAndPerformFetchRequest()
                     }
-                    success?(hasMore)
+                    strongSelf.updateLastSyncedForTopic(objectID)
                 }
+                success?(hasMore)
             }
+        }
 
-            let failureBlock = { (error: Error?) in
-                DispatchQueue.main.async {
-                    if let error = error {
-                        failure?(error as NSError)
-                    }
+        let failureBlock = { (error: Error?) in
+            DispatchQueue.main.async {
+                if let error = error {
+                    failure?(error as NSError)
                 }
             }
-
-            self?.fetch(for: topicInContext, success: successBlock, failure: failureBlock)
         }
+
+        self.fetch(for: topic, success: successBlock, failure: failureBlock)
     }
 
-    func fetch(for topic: ReaderAbstractTopic, success: @escaping ((_ count: Int, _ hasMore: Bool) -> Void), failure: @escaping ((_ error: Error?) -> Void)) {
-        if ReaderHelpers.isTopicSearchTopic(topic) {
-            service.fetchPosts(for: topic, atOffset: 0, deletingEarlier: false, success: success, failure: failure)
-        } else if let topic = topic as? ReaderTagTopic {
-            service.fetchPostsV2(for: topic, success: success, failure: failure)
-        } else {
-            service.fetchPosts(for: topic, earlierThan: Date(), success: success, failure: failure)
+    func fetch(for originalTopic: ReaderAbstractTopic, success: @escaping ((_ count: Int, _ hasMore: Bool) -> Void), failure: @escaping ((_ error: Error?) -> Void)) {
+        coreDataStack.performAndSave { context in
+            guard let topic = (try? context.existingObject(with: originalTopic.objectID)) as? ReaderAbstractTopic else {
+                DDLogError("Error: Could not retrieve an existing topic via its objectID")
+                return
+            }
+
+            let service = ReaderPostService(managedObjectContext: context)
+            if ReaderHelpers.isTopicSearchTopic(topic) {
+                service.fetchPosts(for: topic, atOffset: 0, deletingEarlier: false, success: success, failure: failure)
+            } else if let topic = topic as? ReaderTagTopic {
+                service.fetchPostsV2(for: topic, success: success, failure: failure)
+            } else {
+                service.fetchPosts(for: topic, earlierThan: Date(), success: success, failure: failure)
+            }
         }
     }
 
@@ -1081,8 +1077,8 @@ import Combine
 
         let sortDate = post.sortDate
 
-        syncContext.perform { [weak self] in
-            guard let topicInContext = (try? self?.syncContext.existingObject(with: topic.objectID)) as? ReaderAbstractTopic else {
+        coreDataStack.performAndSave { [weak self] context in
+            guard let topicInContext = (try? context.existingObject(with: topic.objectID)) as? ReaderAbstractTopic else {
                 DDLogError("Error: Could not retrieve an existing topic via its objectID")
                 return
             }
@@ -1110,11 +1106,12 @@ import Combine
                 }
             }
 
+            let service = ReaderPostService(managedObjectContext: context)
             if ReaderHelpers.isTopicSearchTopic(topicInContext) {
                 assertionFailure("Search topics should no have a gap to fill.")
-                self?.service.fetchPosts(for: topicInContext, atOffset: 0, deletingEarlier: true, success: successBlock, failure: failureBlock)
+                service.fetchPosts(for: topicInContext, atOffset: 0, deletingEarlier: true, success: successBlock, failure: failureBlock)
             } else {
-                self?.service.fetchPosts(for: topicInContext, earlierThan: sortDate, deletingEarlier: true, success: successBlock, failure: failureBlock)
+                service.fetchPosts(for: topicInContext, earlierThan: sortDate, deletingEarlier: true, success: successBlock, failure: failureBlock)
             }
         }
     }
@@ -1128,37 +1125,30 @@ import Combine
 
         footerView.showSpinner(true)
 
-        syncContext.perform { [weak self] in
-            guard let topicInContext = (try? self?.syncContext.existingObject(with: topic.objectID)) as? ReaderAbstractTopic else {
-                DDLogError("Error: Could not retrieve an existing topic via its objectID")
-                return
-            }
-
-            let successBlock = { (count: Int, hasMore: Bool) in
-                DispatchQueue.main.async(execute: {
-                    success?(hasMore)
-                })
-            }
-
-            let failureBlock = { (error: Error?) in
-                guard let error = error else {
-                    return
-                }
+        let successBlock = { (count: Int, hasMore: Bool) in
+            DispatchQueue.main.async(execute: {
+                success?(hasMore)
+            })
+        }
 
-                DispatchQueue.main.async(execute: {
-                    failure?(error as NSError)
-                })
+        let failureBlock = { (error: Error?) in
+            guard let error = error else {
+                return
             }
 
-            self?.fetchMore(for: topicInContext, success: successBlock, failure: failureBlock)
+            DispatchQueue.main.async(execute: {
+                failure?(error as NSError)
+            })
         }
 
+        self.fetchMore(for: topic, success: successBlock, failure: failureBlock)
+
         if let properties = topicPropertyForStats() {
             WPAppAnalytics.track(.readerInfiniteScroll, withProperties: properties)
         }
     }
 
-    func fetchMore(for topic: ReaderAbstractTopic, success: @escaping ((Int, Bool) -> Void), failure: @escaping ((Error?) -> Void)) {
+    private func fetchMore(for originalTopic: ReaderAbstractTopic, success: @escaping ((Int, Bool) -> Void), failure: @escaping ((Error?) -> Void)) {
         guard
             let posts = content.content,
             let post = posts.last as? ReaderPost,
@@ -1168,14 +1158,22 @@ import Combine
             return
         }
 
-        if ReaderHelpers.isTopicSearchTopic(topic) {
-            let offset = UInt(content.contentCount)
-            service.fetchPosts(for: topic, atOffset: UInt(offset), deletingEarlier: false, success: success, failure: failure)
-        } else if let topic = topic as? ReaderTagTopic {
-            service.fetchPostsV2(for: topic, isFirstPage: false, success: success, failure: failure)
-        } else {
-            let earlierThan = sortDate
-            service.fetchPosts(for: topic, earlierThan: earlierThan, success: success, failure: failure)
+        coreDataStack.performAndSave { context in
+            guard let topic = (try? context.existingObject(with: originalTopic.objectID)) as? ReaderAbstractTopic else {
+                DDLogError("Error: Could not retrieve an existing topic via its objectID")
+                return
+            }
+
+            let service = ReaderPostService(managedObjectContext: context)
+            if ReaderHelpers.isTopicSearchTopic(topic) {
+                let offset = UInt(self.content.contentCount)
+                service.fetchPosts(for: topic, atOffset: UInt(offset), deletingEarlier: false, success: success, failure: failure)
+            } else if let topic = topic as? ReaderTagTopic {
+                service.fetchPostsV2(for: topic, isFirstPage: false, success: success, failure: failure)
+            } else {
+                let earlierThan = sortDate
+                service.fetchPosts(for: topic, earlierThan: earlierThan, success: success, failure: failure)
+            }
         }
     }