Improve layer view design.

Signal/src/UserInterface/OWSLayerView.swift

@@ -6,35 +6,35 @@ import Foundation
 
 @objc
 class OWSLayerView: UIView {
-    let layoutCallback : (() -> Void)
+    let layoutCallback: ((UIView) -> Void)
 
     @objc
-    public required init(frame: CGRect, layoutCallback : @escaping () -> Void) {
+    public required init(frame: CGRect, layoutCallback : @escaping (UIView) -> Void) {
         self.layoutCallback = layoutCallback
         super.init(frame: frame)
     }
 
     required init?(coder aDecoder: NSCoder) {
-        self.layoutCallback = {
+        self.layoutCallback = { _ in
         }
         super.init(coder: aDecoder)
     }
 
     override var bounds: CGRect {
         didSet {
-            layoutCallback()
+            layoutCallback(self)
         }
     }
 
     override var frame: CGRect {
         didSet {
-            layoutCallback()
+            layoutCallback(self)
         }
     }
 
     override var center: CGPoint {
         didSet {
-            layoutCallback()
+            layoutCallback(self)
         }
     }
 }

Signal/src/ViewControllers/ConversationView/Cells/OWSMessageBubbleView.m

@@ -429,14 +429,14 @@ NS_ASSUME_NONNULL_BEGIN
             (id)[UIColor colorWithWhite:0.f alpha:0.f].CGColor,
             (id)[UIColor colorWithWhite:0.f alpha:0.4f].CGColor,
         ];
-        __block OWSLayerView *gradientView;
-        gradientView = [[OWSLayerView alloc] initWithFrame:CGRectZero
-                                            layoutCallback:^{
-                                                CGRect layerFrame = gradientView.bounds;
-                                                layerFrame.size.height = MIN(maxGradientHeight, gradientView.height);
-                                                layerFrame.origin.y = gradientView.height - layerFrame.size.height;
-                                                gradientLayer.frame = layerFrame;
-                                            }];
+        OWSLayerView *gradientView =
+            [[OWSLayerView alloc] initWithFrame:CGRectZero
+                                 layoutCallback:^(UIView *layerView) {
+                                     CGRect layerFrame = layerView.bounds;
+                                     layerFrame.size.height = MIN(maxGradientHeight, layerView.height);
+                                     layerFrame.origin.y = layerView.height - layerFrame.size.height;
+                                     gradientLayer.frame = layerFrame;
+                                 }];
         [gradientView.layer addSublayer:gradientLayer];
         [bodyMediaView addSubview:gradientView];
         [self.viewConstraints addObjectsFromArray:[gradientView autoPinToSuperviewEdges]];

Signal/src/ViewControllers/CropScaleImageViewController.swift

@@ -155,7 +155,7 @@ import SignalMessaging
         self.view.addSubview(contentView)
         contentView.autoPinEdgesToSuperviewEdges()
 
-        let imageView = OWSLayerView(frame: CGRect.zero, layoutCallback: { [weak self] in
+        let imageView = OWSLayerView(frame: CGRect.zero, layoutCallback: { [weak self] _ in
             guard let strongSelf = self else { return }
             strongSelf.updateImageLayout()
         })