Add video preview to attachment approval dialog.

// FREEBIE

Signal/src/ViewControllers/AttachmentApprovalViewController.swift

@@ -3,6 +3,7 @@
 //
 
 import Foundation
+import MediaPlayer
 
 class AttachmentApprovalViewController: UIViewController {
 
@@ -14,6 +15,8 @@ class AttachmentApprovalViewController: UIViewController {
 
     var successCompletion : (() -> Void)?
 
+    var videoPlayer: MPMoviePlayerController?
+
     // MARK: Initializers
 
     @available(*, unavailable, message:"use attachment: constructor instead.")
@@ -62,6 +65,8 @@ class AttachmentApprovalViewController: UIViewController {
 
         if attachment.isImage {
             createImagePreview(attachmentPreviewView:attachmentPreviewView)
+        } else if attachment.isVideo {
+            createVideoPreview(attachmentPreviewView:attachmentPreviewView)
         } else {
             createGenericPreview(attachmentPreviewView:attachmentPreviewView)
         }
@@ -72,17 +77,38 @@ class AttachmentApprovalViewController: UIViewController {
         if image == nil {
             image = UIImage(data:attachment.data)
         }
-        if image != nil {
-            let imageView = UIImageView(image:image)
-            imageView.layer.minificationFilter = kCAFilterTrilinear
-            imageView.layer.magnificationFilter = kCAFilterTrilinear
-            imageView.contentMode = .scaleAspectFit
-            attachmentPreviewView.addSubview(imageView)
-            imageView.autoPinWidthToSuperview()
-            imageView.autoPinHeightToSuperview()
-        } else {
+        guard image != nil else {
+            createGenericPreview(attachmentPreviewView:attachmentPreviewView)
+            return
+        }
+
+        let imageView = UIImageView(image:image)
+        imageView.layer.minificationFilter = kCAFilterTrilinear
+        imageView.layer.magnificationFilter = kCAFilterTrilinear
+        imageView.contentMode = .scaleAspectFit
+        attachmentPreviewView.addSubview(imageView)
+        imageView.autoPinWidthToSuperview()
+        imageView.autoPinHeightToSuperview()
+    }
+
+    private func createVideoPreview(attachmentPreviewView: UIView) {
+        guard let dataUrl = attachment.getTemporaryDataUrl() else {
             createGenericPreview(attachmentPreviewView:attachmentPreviewView)
+            return
         }
+        guard let videoPlayer = MPMoviePlayerController(contentURL:dataUrl) else {
+            createGenericPreview(attachmentPreviewView:attachmentPreviewView)
+            return
+        }
+        videoPlayer.prepareToPlay()
+
+        videoPlayer.controlStyle = .default
+        videoPlayer.shouldAutoplay = false
+
+        attachmentPreviewView.addSubview(videoPlayer.view)
+        self.videoPlayer = videoPlayer
+        videoPlayer.view.autoPinWidthToSuperview()
+        videoPlayer.view.autoPinHeightToSuperview()
     }
 
     private func createGenericPreview(attachmentPreviewView: UIView) {

Signal/src/ViewControllers/SignalAttachment.swift

@@ -64,6 +64,8 @@ class SignalAttachment: NSObject {
 
     let data: Data
 
+    internal var temporaryDataUrl: URL?
+
     // Attachment types are identified using UTIs.
     //
     // See: https://developer.apple.com/library/content/documentation/Miscellaneous/Reference/UTIRef/Articles/System-DeclaredUniformTypeIdentifiers.html
@@ -109,6 +111,29 @@ class SignalAttachment: NSObject {
         super.init()
     }
 
+    // MARK: Methods
+
+    public func getTemporaryDataUrl() -> URL? {
+        if temporaryDataUrl == nil {
+            let directory = NSTemporaryDirectory()
+            guard let fileExtension = self.fileExtension else {
+                return nil
+            }
+            let fileName = NSUUID().uuidString + "." + fileExtension
+            guard let fileUrl = NSURL.fileURL(withPathComponents: [directory, fileName]) else {
+                return nil
+            }
+            do {
+                try data.write(to: fileUrl)
+            } catch {
+                Logger.info("\(SignalAttachment.TAG) Could not write data to disk: \(dataUTI)")
+                return nil
+            }
+            temporaryDataUrl = fileUrl
+        }
+        return temporaryDataUrl
+    }
+
     var hasError: Bool {
         return error != nil
     }