More code review polish.

Signal/src/ViewControllers/HomeView/HomeViewController.m

@@ -226,7 +226,7 @@ NSString *const kArchivedConversationsReuseIdentifier = @"kArchivedConversations
 
     [emptyBoxLabel autoPinLeadingToSuperviewMargin];
     [emptyBoxLabel autoPinTrailingToSuperviewMargin];
-    [emptyBoxLabel autoPinVCenterToSuperviewVCenter];
+    [emptyBoxLabel autoAlignAxisToSuperviewAxis:ALAxisHorizontal];
 
     UIRefreshControl *pullToRefreshView = [UIRefreshControl new];
     pullToRefreshView.tintColor = [UIColor grayColor];

SignalMessaging/categories/UIView+OWS.h

@@ -88,7 +88,6 @@ CGFloat ScaleFromIPhone5(CGFloat iPhone5Value);
 - (NSLayoutConstraint *)autoPinTopToSuperviewMarginWithInset:(CGFloat)margin;
 - (NSLayoutConstraint *)autoPinBottomToSuperviewMargin;
 - (NSLayoutConstraint *)autoPinBottomToSuperviewMarginWithInset:(CGFloat)margin;
-- (NSLayoutConstraint *)autoPinVCenterToSuperviewVCenter;
 
 - (NSLayoutConstraint *)autoPinLeadingToTrailingEdgeOfView:(UIView *)view;
 - (NSLayoutConstraint *)autoPinLeadingToTrailingEdgeOfView:(UIView *)view offset:(CGFloat)margin;

SignalMessaging/categories/UIView+OWS.m

@@ -302,14 +302,6 @@ CGFloat ScaleFromIPhone5(CGFloat iPhone5Value)
     return constraint;
 }
 
-- (NSLayoutConstraint *)autoPinVCenterToSuperviewVCenter {
-    self.translatesAutoresizingMaskIntoConstraints = NO;
-
-    NSLayoutConstraint *constraint = [self.centerYAnchor constraintEqualToAnchor:self.superview.centerYAnchor];
-    constraint.active = YES;
-    return constraint;
-}
-
 - (NSLayoutConstraint *)autoPinTopToSuperviewMargin
 {
     return [self autoPinTopToSuperviewMarginWithInset:0.f];