From 41977f74374f3509ca58a34fd96df473e35e9878 Mon Sep 17 00:00:00 2001
From: Michael Kirk <michael@signal.org>
Date: Mon, 22 Apr 2019 12:08:34 -0700
Subject: [PATCH] snappier presentation of collection picker

---
 .../Photos/ImagePickerController.swift        | 38 +++++++++----------
 .../PhotoCollectionPickerController.swift     |  3 --
 2 files changed, 19 insertions(+), 22 deletions(-)

diff --git a/Signal/src/ViewControllers/Photos/ImagePickerController.swift b/Signal/src/ViewControllers/Photos/ImagePickerController.swift
index 5912c7214..8ecbd9ae4 100644
--- a/Signal/src/ViewControllers/Photos/ImagePickerController.swift
+++ b/Signal/src/ViewControllers/Photos/ImagePickerController.swift
@@ -226,6 +226,11 @@ class ImagePickerGridController: UICollectionViewController, PhotoLibraryDelegat
         // We don't need to do this when pushing VCs onto the SignalsNavigationController - only when
         // presenting directly from ConversationVC.
         _ = self.becomeFirstResponder()
+
+        DispatchQueue.main.async {
+            // pre-layout collectionPicker for snappier response
+            self.collectionPickerController.view.layoutIfNeeded()
+        }
     }
 
     // HACK: Though we don't have an input accessory view, the VC we are presented above (ConversationVC) does.
@@ -401,26 +406,23 @@ class ImagePickerGridController: UICollectionViewController, PhotoLibraryDelegat
 
     // MARK: - PhotoCollectionPicker Presentation
 
-    var isShowingCollectionPickerController: Bool {
-        return collectionPickerController != nil
-    }
+    var isShowingCollectionPickerController: Bool = false
+
+    lazy var collectionPickerController: PhotoCollectionPickerController = {
+        return PhotoCollectionPickerController(library: library,
+                                               collectionDelegate: self)
+    }()
 
-    var collectionPickerController: PhotoCollectionPickerController?
     func showCollectionPicker() {
         Logger.debug("")
 
-        let collectionPickerController = PhotoCollectionPickerController(library: library,
-                                                                         previousPhotoCollection: photoCollection,
-                                                                         collectionDelegate: self)
-
         guard let collectionPickerView = collectionPickerController.view else {
             owsFailDebug("collectionView was unexpectedly nil")
             return
         }
 
-        assert(self.collectionPickerController == nil)
-        self.collectionPickerController = collectionPickerController
-
+        assert(!isShowingCollectionPickerController)
+        isShowingCollectionPickerController = true
         addChild(collectionPickerController)
 
         view.addSubview(collectionPickerView)
@@ -439,18 +441,16 @@ class ImagePickerGridController: UICollectionViewController, PhotoLibraryDelegat
 
     func hideCollectionPicker() {
         Logger.debug("")
-        guard let collectionPickerController = collectionPickerController else {
-            owsFailDebug("collectionPickerController was unexpectedly nil")
-            return
-        }
-        self.collectionPickerController = nil
+
+        assert(isShowingCollectionPickerController)
+        isShowingCollectionPickerController = false
 
         UIView.animate(.promise, duration: 0.25, delay: 0, options: .curveEaseInOut) {
-            collectionPickerController.view.frame = self.view.frame.offsetBy(dx: 0, dy: self.view.frame.height)
+            self.collectionPickerController.view.frame = self.view.frame.offsetBy(dx: 0, dy: self.view.frame.height)
             self.titleView.rotateIcon(.down)
         }.done { _ in
-            collectionPickerController.view.removeFromSuperview()
-            collectionPickerController.removeFromParent()
+            self.collectionPickerController.view.removeFromSuperview()
+            self.collectionPickerController.removeFromParent()
         }.retainUntilComplete()
     }
 
diff --git a/Signal/src/ViewControllers/Photos/PhotoCollectionPickerController.swift b/Signal/src/ViewControllers/Photos/PhotoCollectionPickerController.swift
index d551da139..a0b070b64 100644
--- a/Signal/src/ViewControllers/Photos/PhotoCollectionPickerController.swift
+++ b/Signal/src/ViewControllers/Photos/PhotoCollectionPickerController.swift
@@ -15,14 +15,11 @@ class PhotoCollectionPickerController: OWSTableViewController, PhotoLibraryDeleg
     private weak var collectionDelegate: PhotoCollectionPickerDelegate?
 
     private let library: PhotoLibrary
-    private let previousPhotoCollection: PhotoCollection
     private var photoCollections: [PhotoCollection]
 
     required init(library: PhotoLibrary,
-                  previousPhotoCollection: PhotoCollection,
                   collectionDelegate: PhotoCollectionPickerDelegate) {
         self.library = library
-        self.previousPhotoCollection = previousPhotoCollection
         self.photoCollections = library.allPhotoCollections()
         self.collectionDelegate = collectionDelegate
         super.init()