filter caption strings for display

Signal/src/ViewControllers/MediaGalleryViewController.swift

@@ -4,6 +4,12 @@
 
 import Foundation
 
+extension String {
+    var filterForDisplay: String? {
+        return (self as NSString).filterStringForDisplay()
+    }
+}
+
 public enum GalleryDirection {
     case before, after, around
 }
@@ -12,10 +18,12 @@ public class MediaGalleryItem: Equatable, Hashable {
     let message: TSMessage
     let attachmentStream: TSAttachmentStream
     let galleryDate: GalleryDate
+    let captionForDisplay: String?
 
     init(message: TSMessage, attachmentStream: TSAttachmentStream) {
         self.message = message
         self.attachmentStream = attachmentStream
+        self.captionForDisplay = attachmentStream.caption?.filterForDisplay
         self.galleryDate = GalleryDate(message: message)
     }
 
@@ -31,10 +39,6 @@ public class MediaGalleryItem: Equatable, Hashable {
         return attachmentStream.isImage
     }
 
-    var caption: String? {
-        return attachmentStream.caption
-    }
-
     public typealias AsyncThumbnailBlock = (UIImage) -> Void
     func thumbnailImage(async:@escaping AsyncThumbnailBlock) -> UIImage? {
         return attachmentStream.thumbnailImageSmall(success: async, failure: {})

Signal/src/ViewControllers/MediaPageViewController.swift

@@ -172,7 +172,7 @@ class MediaPageViewController: UIPageViewController, UIPageViewControllerDataSou
         captionViewsContainer.addSubview(currentCaptionView)
         currentCaptionView.autoPinEdgesToSuperviewEdges(with: .zero, excludingEdge: .top)
         currentCaptionView.autoPinEdge(toSuperviewEdge: .top, withInset: 0, relation: .greaterThanOrEqual)
-        currentCaptionView.text = currentItem.caption
+        currentCaptionView.text = currentItem.captionForDisplay
 
         let pendingCaptionView = CaptionView()
         self.pendingCaptionView = pendingCaptionView
@@ -447,7 +447,7 @@ class MediaPageViewController: UIPageViewController, UIPageViewControllerDataSou
 
             CATransaction.begin()
             CATransaction.disableActions()
-            if let pendingCaptionText = pendingViewController.galleryItem.caption, pendingCaptionText.count > 0 {
+            if let pendingCaptionText = pendingViewController.galleryItem.captionForDisplay, pendingCaptionText.count > 0 {
                 self.pendingCaptionView.text = pendingCaptionText
             } else {
                 self.pendingCaptionView.text = nil