Use SignalAttachment logic in conversation view too

// FREEBIE

Signal/src/ViewControllers/ConversationView/ConversationViewController.m

@@ -62,6 +62,7 @@
 #import <JSQSystemSoundPlayer/JSQSystemSoundPlayer.h>
 #import <MediaPlayer/MediaPlayer.h>
 #import <MobileCoreServices/UTCoreTypes.h>
+#import <PromiseKit/AnyPromise.h>
 #import <SignalMessaging/OWSContactOffersInteraction.h>
 #import <SignalMessaging/OWSFormat.h>
 #import <SignalMessaging/OWSUserProfile.h>
@@ -2722,37 +2723,22 @@ typedef NS_ENUM(NSInteger, MessagesRangeSizeMode) {
         presentFromViewController:self
                         canCancel:YES
                   backgroundBlock:^(ModalActivityIndicatorViewController *modalActivityIndicator) {
-                      AVAsset *video = [AVAsset assetWithURL:movieURL];
+                      DataSource *dataSource = [DataSourcePath dataSourceWithURL:movieURL];
-                      AVAssetExportSession *exportSession =
+                      dataSource.sourceFilename = filename;
-                          [AVAssetExportSession exportSessionWithAsset:video
+                      VideoCompressionResult *compressionResult =
-                                                            presetName:AVAssetExportPresetMediumQuality];
+                          [SignalAttachment compressVideoAsMp4WithDataSource:dataSource
-                      exportSession.shouldOptimizeForNetworkUse = YES;
+                                                                     dataUTI:(NSString *)kUTTypeMPEG4];
-                      exportSession.outputFileType = AVFileTypeMPEG4;
+                      [compressionResult.attachmentPromise retainUntilComplete];
-                      NSURL *compressedVideoUrl = [[self videoTempFolder]
+
-                          URLByAppendingPathComponent:[[[NSUUID UUID] UUIDString]
+                      compressionResult.attachmentPromise.then(^(SignalAttachment *attachment) {
-                                                          stringByAppendingPathExtension:@"mp4"]];
-                      exportSession.outputURL = compressedVideoUrl;
-                      [exportSession exportAsynchronouslyWithCompletionHandler:^{
-                          dispatch_async(dispatch_get_main_queue(), ^{
                           OWSAssert([NSThread isMainThread]);
+                          OWSAssert([attachment isKindOfClass:[SignalAttachment class]]);
 
                           if (modalActivityIndicator.wasCancelled) {
                               return;
                           }
 
                           [modalActivityIndicator dismissWithCompletion:^{
-                                  
-                                  NSString *baseFilename = filename.stringByDeletingPathExtension;
-                                  NSString *mp4Filename = [baseFilename stringByAppendingPathExtension:@"mp4"];
-                                  DataSource *_Nullable dataSource =
-                                      [DataSourcePath dataSourceWithURL:compressedVideoUrl];
-                                  [dataSource setSourceFilename:mp4Filename];
-                                  
-                                  // Remove temporary file when complete.
-                                  [dataSource setShouldDeleteOnDeallocation];
-                                  SignalAttachment *attachment =
-                                      [SignalAttachment attachmentWithDataSource:dataSource
-                                                                         dataUTI:(NSString *)kUTTypeMPEG4];
                               if (!attachment || [attachment hasError]) {
                                   DDLogError(@"%@ %s Invalid attachment: %@.",
                                       self.logTag,
@@ -2760,13 +2746,11 @@ typedef NS_ENUM(NSInteger, MessagesRangeSizeMode) {
                                       attachment ? [attachment errorName] : @"Missing data");
                                   [self showErrorAlertForAttachment:attachment];
                               } else {
-                                      [self tryToSendAttachmentIfApproved:attachment
+                                  [self tryToSendAttachmentIfApproved:attachment skipApprovalDialog:skipApprovalDialog];
-                                                       skipApprovalDialog:skipApprovalDialog];
                               }
                           }];
                       });
                   }];
-                  }];
 }
 
 

SignalMessaging/attachments/SignalAttachment.swift

@@ -866,6 +866,27 @@ public class SignalAttachment: NSObject {
         return (promise, exportSession)
     }
 
+    @objc
+    public class VideoCompressionResult: NSObject {
+        @objc
+        public let attachmentPromise: AnyPromise
+
+        @objc
+        public let exportSession: AVAssetExportSession?
+
+        fileprivate init(attachmentPromise: Promise<SignalAttachment>, exportSession: AVAssetExportSession?) {
+            self.attachmentPromise = AnyPromise(attachmentPromise)
+            self.exportSession = exportSession
+            super.init()
+        }
+    }
+
+    @objc
+    public class func compressVideoAsMp4(dataSource: DataSource, dataUTI: String) -> VideoCompressionResult {
+        let (attachmentPromise, exportSession) = compressVideoAsMp4(dataSource: dataSource, dataUTI: dataUTI)
+        return VideoCompressionResult(attachmentPromise: attachmentPromise, exportSession: exportSession)
+    }
+
     public class func isInvalidVideo(dataSource: DataSource, dataUTI: String) -> Bool {
         guard videoUTISet.contains(dataUTI) else {
             // not a video

SignalMessaging/categories/Promise+retainUntilComplete.swift

@@ -4,6 +4,21 @@
 
 import PromiseKit
 
+public extension AnyPromise {
+    /**
+     * Sometimes there isn't a straight forward candidate to retain a promise, in that case we tell the
+     * promise to self retain, until it completes to avoid the risk it's GC'd before completion.
+     */
+    func retainUntilComplete() {
+        // Unfortunately, there is (currently) no way to surpress the
+        // compiler warning: "Variable 'retainCycle' was written to, but never read"
+        var retainCycle: AnyPromise? = self
+        self.always {
+            retainCycle = nil
+        }
+    }
+}
+
 public extension Promise {
     /**
      * Sometimes there isn't a straight forward candidate to retain a promise, in that case we tell the