Attempt to workaround crash #1034

Author: chrisballinger

ChatSecure/Classes/Controllers/FileTransferManager.swift

@@ -155,14 +155,16 @@ public class FileTransferManager: NSObject, OTRServerCapabilitiesDelegate {
 
     // Resume downloads, i.e. look for media items that are partially downloaded and retry getting them. TODO - use ranges
     @objc public func resumeDownloads() {
-        connection.asyncRead { (transaction) in
-            transaction.enumerateUnfinishedDownloads({ (mediaItem, stop) in
-                if let downloadMessage = mediaItem.parentObject(with: transaction) as? OTRDownloadMessage, downloadMessage.messageError == nil {
-                    self.internalQueue.async {
-                        self.downloadMedia(downloadMessage)
+        connection.asyncRead { [weak self] (transaction) in
+            let unfinished = transaction.unfinishedDownloads()
+            self?.internalQueue.async {
+                for mediaItem in unfinished {
+                    if let downloadMessage = mediaItem.parentObject(with: transaction) as? OTRDownloadMessage,
+                        downloadMessage.messageError == nil {
+                        self?.downloadMedia(downloadMessage)
                     }
                 }
-            })
+            }
         }
     }
 

ChatSecure/Classes/Controllers/YapDatabaseTransaction+ChatSecure.swift

@@ -148,18 +148,20 @@ public extension YapDatabaseReadTransaction {
 
 public extension YapDatabaseReadTransaction {
 
-    @objc public func enumerateUnfinishedDownloads(_ block:@escaping (_ mediaItem:OTRMediaItem,_ stop:UnsafeMutablePointer<ObjCBool>) -> Void) {
+    public func unfinishedDownloads() -> [OTRMediaItem] {
         guard let secondaryIndexTransaction = self.ext(SecondaryIndexName.mediaItems) as? YapDatabaseSecondaryIndexTransaction else {
-            return
+            return []
         }
+        var unfinished: [OTRMediaItem] = []
         let queryString = "Where \(MediaItemIndexColumnName.transferProgress) < 1 AND \(MediaItemIndexColumnName.isIncoming) == 1"
         let query = YapDatabaseQuery(string: queryString, parameters: [])
         secondaryIndexTransaction.enumerateKeysAndObjects(matching: query) { (key, collection, object, stop) in
             if let download = object as? OTRMediaItem {
-                block(download, stop)
+                unfinished.append(download)
             } else {
                 DDLogError("Non-media item object in downloads index \(object)")
             }
         }
+        return unfinished
     }
 }