Move QR code scanning to a separate view.

// FREEBIE

Signal/src/ViewControllers/ConversationView/MessagesViewController.m

@@ -2535,7 +2535,7 @@ typedef enum : NSUInteger {
 
 - (void)createScrollDownButton
 {
-    const CGFloat kScrollDownButtonSize = round(ScaleFromIPhone5To7Plus(35.f, 40.f));
+    const CGFloat kScrollDownButtonSize = ScaleFromIPhone5To7Plus(35.f, 40.f);
     UIButton *scrollDownButton = [UIButton buttonWithType:UIButtonTypeCustom];
     self.scrollDownButton = scrollDownButton;
     scrollDownButton.backgroundColor = [UIColor colorWithWhite:0.95f alpha:1.f];

Signal/src/ViewControllers/FingerprintViewScanController.m

@@ -79,15 +79,16 @@ NS_ASSUME_NONNULL_BEGIN
     UILabel *cameraInstructionLabel = [UILabel new];
     cameraInstructionLabel.text
         = NSLocalizedString(@"SCAN_CODE_INSTRUCTIONS", @"label presented once scanning (camera) view is visible.");
-    cameraInstructionLabel.font = [UIFont ows_regularFontWithSize:14.f];
+    cameraInstructionLabel.font = [UIFont ows_regularFontWithSize:ScaleFromIPhone5To7Plus(14.f, 18.f)];
     cameraInstructionLabel.textColor = [UIColor whiteColor];
     cameraInstructionLabel.textAlignment = NSTextAlignmentCenter;
     cameraInstructionLabel.numberOfLines = 0;
     cameraInstructionLabel.lineBreakMode = NSLineBreakByWordWrapping;
     [footer addSubview:cameraInstructionLabel];
-    [cameraInstructionLabel autoPinWidthToSuperviewWithMargin:16.f];
-    [cameraInstructionLabel autoPinEdgeToSuperviewEdge:ALEdgeBottom withInset:10.f];
-    [cameraInstructionLabel autoPinEdgeToSuperviewEdge:ALEdgeTop withInset:10.f];
+    [cameraInstructionLabel autoPinWidthToSuperviewWithMargin:ScaleFromIPhone5To7Plus(16.f, 30.f)];
+    CGFloat instructionsVMargin = ScaleFromIPhone5To7Plus(10.f, 20.f);
+    [cameraInstructionLabel autoPinEdgeToSuperviewEdge:ALEdgeBottom withInset:instructionsVMargin];
+    [cameraInstructionLabel autoPinEdgeToSuperviewEdge:ALEdgeTop withInset:instructionsVMargin];
 }
 
 - (void)viewWillAppear:(BOOL)animated

Signal/src/ViewControllers/OWSQRCodeScanningViewController.m

@@ -57,8 +57,8 @@
     [maskingView setConfigureShapeLayerBlock:^(CAShapeLayer *layer, CGRect bounds) {
         // Add a circular mask
         UIBezierPath *path = [UIBezierPath bezierPathWithRect:bounds];
-        CGFloat verticalMargin = 8.0;
-        CGFloat radius = MIN(bounds.size.width, bounds.size.height) * 0.5f - verticalMargin;
+        CGFloat margin = ScaleFromIPhone5To7Plus(8.f, 16.f);
+        CGFloat radius = MIN(bounds.size.width, bounds.size.height) * 0.5f - margin;
 
         // Center the circle's bounding rectangle
         CGRect circleRect = CGRectMake(