Add link previews to converastion view items.

Signal/src/ViewControllers/ColorPickerViewController.swift

@@ -341,6 +341,8 @@ private class MockConversationViewItem: NSObject, ConversationViewItem {
     var hasMediaActionContent: Bool = false
     var mediaAlbumItems: [ConversationMediaAlbumItem]?
     var hasCachedLayoutState: Bool = false
+    var linkPreview: OWSLinkPreview?
+    var linkPreviewAttachment: TSAttachment?
 
     override init() {
         super.init()

Signal/src/ViewControllers/ConversationView/ConversationViewItem.h

@@ -26,6 +26,7 @@ NSString *NSStringForOWSMessageCellType(OWSMessageCellType cellType);
 @class ConversationViewCell;
 @class DisplayableText;
 @class OWSAudioMessageView;
+@class OWSLinkPreview;
 @class OWSQuotedReplyModel;
 @class OWSUnreadIndicator;
 @class TSAttachment;
@@ -121,6 +122,9 @@ NSString *NSStringForOWSMessageCellType(OWSMessageCellType cellType);
 
 @property (nonatomic, readonly, nullable) ContactShareViewModel *contactShare;
 
+@property (nonatomic, readonly, nullable) OWSLinkPreview *linkPreview;
+@property (nonatomic, readonly, nullable) TSAttachment *linkPreviewAttachment;
+
 @property (nonatomic, readonly, nullable) NSString *systemMessageText;
 
 // NOTE: This property is only set for incoming messages.

Signal/src/ViewControllers/ConversationView/ConversationViewItem.m

@@ -97,6 +97,8 @@ NSString *NSStringForOWSMessageCellType(OWSMessageCellType cellType)
 @property (nonatomic, nullable) TSAttachmentStream *attachmentStream;
 @property (nonatomic, nullable) TSAttachmentPointer *attachmentPointer;
 @property (nonatomic, nullable) ContactShareViewModel *contactShare;
+@property (nonatomic, nullable) OWSLinkPreview *linkPreview;
+@property (nonatomic, nullable) TSAttachment *linkPreviewAttachment;
 @property (nonatomic, nullable) NSArray<ConversationMediaAlbumItem *> *mediaAlbumItems;
 @property (nonatomic, nullable) NSString *systemMessageText;
 @property (nonatomic, nullable) TSThread *incomingMessageAuthorThread;
@@ -158,10 +160,14 @@ NSString *NSStringForOWSMessageCellType(OWSMessageCellType cellType)
     self.displayableBodyText = nil;
     self.attachmentStream = nil;
     self.attachmentPointer = nil;
+    self.mediaAlbumItems = nil;
     self.displayableQuotedText = nil;
     self.quotedReply = nil;
+    self.contactShare = nil;
     self.systemMessageText = nil;
-    self.mediaAlbumItems = nil;
+    self.authorConversationColorName = nil;
+    self.linkPreview = nil;
+    self.linkPreviewAttachment = nil;
 
     [self updateAuthorConversationColorNameWithTransaction:transaction];
 
@@ -660,6 +666,17 @@ NSString *NSStringForOWSMessageCellType(OWSMessageCellType cellType)
         OWSAssertDebug(self.displayableBodyText);
     }
 
+    if (self.hasBodyText && attachment == nil && message.linkPreview) {
+        self.linkPreview = message.linkPreview;
+        if (message.linkPreview.imageAttachmentId.length > 0) {
+            self.linkPreviewAttachment =
+                [TSAttachment fetchObjectWithUniqueID:message.linkPreview.imageAttachmentId transaction:transaction];
+            if (!self.linkPreviewAttachment) {
+                OWSFailDebug(@"Could not load link preview image attachment.");
+            }
+        }
+    }
+
     if (self.messageCellType == OWSMessageCellType_Unknown) {
         // Messages of unknown type (including messages with missing attachments)
         // are rendered like empty text messages, but without any interactivity.

Signal/src/views/LinkPreviewView.swift

@@ -369,11 +369,11 @@ public class LinkPreviewView: UIStackView {
         self.alignment = .center
         self.autoSetDimension(.height, toSize: approvalHeight)
 
-        let label = UILabel()
-        label.text = NSLocalizedString("LINK_PREVIEW_LOADING", comment: "Indicates that the link preview is being loaded.")
-        label.textColor = Theme.secondaryColor
-        label.font = UIFont.ows_dynamicTypeBody
-        addArrangedSubview(label)
+        let activityIndicator = UIActivityIndicatorView(activityIndicatorStyle: .gray)
+        activityIndicator.startAnimating()
+        addArrangedSubview(activityIndicator)
+        let activityIndicatorSize: CGFloat = 25
+        activityIndicator.autoSetDimensions(to: CGSize(width: activityIndicatorSize, height: activityIndicatorSize))
     }
 
     // MARK: Events