Fix spacing of custom back button

...and use it (only) in Messages VC

Otherwise we'd have to do lots of manual handling of
interactivePopGesture

// FREEBIE

Signal/src/util/UIViewController+OWS.h

@@ -8,8 +8,14 @@ NS_ASSUME_NONNULL_BEGIN
 
 @interface UIViewController (OWS)
 
+/**
+ * Takes up a bit less space than the default system back button
+ * used in the MessagesViewController to help left-align the title view.
+ *
+ * **note** Using this breaks the interactive pop gesture (swipe back) unless you set/unset the 
+ * interactivePopGesture.delegate to self/nil on viewWillAppear/Disappear
+ */
 - (UIBarButtonItem *)createOWSBackButton;
-- (void)useOWSBackButton;
 
 @end
 

Signal/src/util/UIViewController+OWS.m

@@ -10,18 +10,39 @@ NS_ASSUME_NONNULL_BEGIN
 
 - (UIBarButtonItem *)createOWSBackButton
 {
+    // Nudge closer to the left edge to match default back button item.
+    const CGFloat kExtraLeftPadding = -8;
+
+    // Give some extra hit area to the back button. This is a little smaller
+    // than the default back button, but makes sense for our left aligned title
+    // view in the MessagesViewController
+    const CGFloat kExtraRightPadding = 10;
+
+    // Extra hit area above/below
+    const CGFloat kExtraHeightPadding = 4;
+
+    // Matching the default backbutton placement is tricky.
+    // We can't just adjust the imageEdgeInsets on a UIBarButtonItem directly,
+    // so we adjust the imageEdgeInsets on a UIButton, then wrap that
+    // in a UIBarButtonItem.
+    UIButton *backButton = [UIButton buttonWithType:UIButtonTypeCustom];
+    [backButton addTarget:self action:@selector(backButtonPressed:) forControlEvents:UIControlEventTouchUpInside];
+
     UIImage *backImage = [UIImage imageNamed:@"NavBarBack"];
     OWSAssert(backImage);
-    UIBarButtonItem *backItem = [[UIBarButtonItem alloc] initWithImage:backImage
-                                                                 style:UIBarButtonItemStylePlain
-                                                                target:self
-                                                                action:@selector(backButtonPressed:)];
-    return backItem;
-}
+    [backButton setImage:backImage forState:UIControlStateNormal];
 
-- (void)useOWSBackButton
-{
-    self.navigationItem.leftBarButtonItem = [self createOWSBackButton];
+    backButton.contentHorizontalAlignment = UIControlContentHorizontalAlignmentLeft;
+
+    // Default back button is 1.5 pixel lower than our extracted image.
+    const CGFloat kTopInsetPadding = 1.5
+    backButton.imageEdgeInsets = UIEdgeInsetsMake(kTopInsetPadding, kExtraLeftPadding, 0, 0);
+
+    backButton.frame = CGRectMake(0, 0, backImage.size.width + kExtraRightPadding, backImage.size.height + kExtraHeightPadding);
+
+    UIBarButtonItem *backItem = [[UIBarButtonItem alloc] initWithCustomView:backButton];
+
+    return backItem;
 }
 
 #pragma mark - Event Handling

Signal/src/view controllers/AboutTableViewController.m

@@ -5,7 +5,6 @@
 #import <Social/Social.h>
 #import "AboutTableViewController.h"
 #import "UIUtil.h"
-#import "UIViewController+OWS.h"
 
 @interface AboutTableViewController ()
 
@@ -33,7 +32,6 @@ typedef NS_ENUM(NSUInteger, AboutTableViewControllerSection) {
 - (void)viewDidLoad {
     [super viewDidLoad];
     [self.navigationController.navigationBar setTranslucent:NO];
-    [self useOWSBackButton];
     self.tableView.tableFooterView = [[UIView alloc] initWithFrame:CGRectZero];
 }
 

Signal/src/view controllers/AdvancedSettingsTableViewController.m

@@ -10,7 +10,6 @@
 #import "RPAccountManager.h"
 #import "Signal-Swift.h"
 #import "TSAccountManager.h"
-#import "UIViewController+OWS.h"
 #import "Pastelog.h"
 #import <PromiseKit/AnyPromise.h>
 
@@ -52,8 +51,6 @@ typedef NS_ENUM(NSInteger, AdvancedSettingsTableViewControllerSection) {
 
     self.title = NSLocalizedString(@"SETTINGS_ADVANCED_TITLE", @"");
     
-    [self useOWSBackButton];
-    
     // Enable Log
     self.enableLogCell                        = [[UITableViewCell alloc] init];
     self.enableLogCell.textLabel.text         = NSLocalizedString(@"SETTINGS_ADVANCED_DEBUGLOG", @"");

Signal/src/view controllers/FingerprintViewController.m

@@ -8,7 +8,6 @@
 #import "Signal-Swift.h"
 #import "UIUtil.h"
 #import "UIViewController+CameraPermissions.h"
-#import "UIViewController+OWS.h"
 #import <SignalServiceKit/NSDate+millisecondTimeStamp.h>
 #import <SignalServiceKit/OWSError.h>
 #import <SignalServiceKit/OWSFingerprint.h>

Signal/src/view controllers/MessageComposeTableViewController.m

@@ -13,7 +13,6 @@
 #import "Signal-Swift.h"
 #import "UIColor+OWS.h"
 #import "UIUtil.h"
-#import "UIViewController+OWS.h"
 
 NS_ASSUME_NONNULL_BEGIN
 

Signal/src/view controllers/NewGroupViewController.m

@@ -12,7 +12,6 @@
 #import "TSOutgoingMessage.h"
 #import "UIImage+normalizeImage.h"
 #import "UIUtil.h"
-#import "UIViewController+OWS.h"
 #import <MobileCoreServices/UTCoreTypes.h>
 #import <SignalServiceKit/MimeTypeUtil.h>
 #import <SignalServiceKit/NSDate+millisecondTimeStamp.h>
@@ -101,7 +100,6 @@ static NSString *const kUnwindToMessagesViewSegue = @"UnwindToMessagesViewSegue"
 - (void)viewDidLoad {
     [super viewDidLoad];
     [self.navigationController.navigationBar setTranslucent:NO];
-    [self useOWSBackButton];
     
     contacts = self.contactsManager.signalContacts;
 

Signal/src/view controllers/NotificationSettingsOptionsViewController.m

@@ -5,7 +5,6 @@
 #import "NotificationSettingsOptionsViewController.h"
 #import "Environment.h"
 #import "PropertyListPreferences.h"
-#import "UIViewController+OWS.h"
 
 @interface NotificationSettingsOptionsViewController ()
 
@@ -19,8 +18,6 @@
     self.options = @[ @(NotificationNamePreview), @(NotificationNameNoPreview), @(NotificationNoNameNoPreview) ];
 
     [super viewDidLoad];
-
-    [self useOWSBackButton];
 }
 
 #pragma mark - Table view data source

Signal/src/view controllers/NotificationSettingsViewController.m

@@ -6,7 +6,6 @@
 #import "Environment.h"
 #import "NotificationSettingsOptionsViewController.h"
 #import "PropertyListPreferences.h"
-#import "UIViewController+OWS.h"
 
 #define kNotificationOptionSection 0
 
@@ -26,8 +25,6 @@
     [super viewDidLoad];
     [self setTitle:NSLocalizedString(@"SETTINGS_NOTIFICATIONS", nil)];
 
-    [self useOWSBackButton];
-
     self.notificationsSections = @[
         NSLocalizedString(@"NOTIFICATIONS_SECTION_BACKGROUND", nil),
         NSLocalizedString(@"NOTIFICATIONS_SECTION_INAPP", nil)

Signal/src/view controllers/OWSConversationSettingsTableViewController.m

@@ -12,7 +12,6 @@
 #import "ShowGroupMembersViewController.h"
 #import "UIFont+OWS.h"
 #import "UIUtil.h"
-#import "UIViewController+OWS.h"
 #import <25519/Curve25519.h>
 #import <SignalServiceKit/NSDate+millisecondTimeStamp.h>
 #import <SignalServiceKit/OWSDisappearingConfigurationUpdateInfoMessage.h>
@@ -179,8 +178,6 @@ static NSString *const OWSConversationSettingsTableViewControllerSegueShowGroupM
     self.listGroupMembersCell.textLabel.text
         = NSLocalizedString(@"LIST_GROUP_MEMBERS_ACTION", @"table cell label in conversation settings");
 
-    [self useOWSBackButton];
-
     self.toggleDisappearingMessagesCell.selectionStyle = UITableViewCellSelectionStyleNone;
     self.disappearingMessagesDurationCell.selectionStyle = UITableViewCellSelectionStyleNone;
 
@@ -212,9 +209,6 @@ static NSString *const OWSConversationSettingsTableViewControllerSegueShowGroupM
 {
     [super viewWillAppear:animated];
 
-    // Since we're using a custom back button, we have to do some extra work to manage the interactivePopGestureRecognizer
-    self.navigationController.interactivePopGestureRecognizer.delegate = self;
-
     // HACK to unselect rows when swiping back
     // http://stackoverflow.com/questions/19379510/uitableviewcell-doesnt-get-deselected-when-swiping-back-quickly
     [self.tableView deselectRowAtIndexPath:[self.tableView indexPathForSelectedRow] animated:animated];
@@ -224,9 +218,6 @@ static NSString *const OWSConversationSettingsTableViewControllerSegueShowGroupM
 {
     [super viewWillDisappear:animated];
 
-    // Since we're using a custom back button, we have to do some extra work to manage the interactivePopGestureRecognizer
-    self.navigationController.interactivePopGestureRecognizer.delegate = nil;
-
     if (self.disappearingMessagesConfiguration.isNewRecord && !self.disappearingMessagesConfiguration.isEnabled) {
         // don't save defaults, else we'll unintentionally save the configuration and notify the contact.
         return;

Signal/src/view controllers/OWSLinkDeviceViewController.m

@@ -6,7 +6,6 @@
 #import "OWSDeviceProvisioningURLParser.h"
 #import "OWSLinkedDevicesTableViewController.h"
 #import "SettingsTableViewController.h"
-#import "UIViewController+OWS.h"
 #import <SignalServiceKit/ECKeyPair+OWSPrivateKey.h>
 #import <SignalServiceKit/OWSDeviceProvisioner.h>
 #import <SignalServiceKit/TSStorageManager+IdentityKeyStore.h>
@@ -28,8 +27,6 @@ NS_ASSUME_NONNULL_BEGIN
 {
     [super viewDidLoad];
 
-    [self useOWSBackButton];
-
     // HACK to get full width preview layer
     CGRect oldFrame = self.qrScanningView.frame;
     self.qrScanningView.frame = CGRectMake(

Signal/src/view controllers/OWSLinkedDevicesTableViewController.m

@@ -6,7 +6,6 @@
 #import "OWSDeviceTableViewCell.h"
 #import "OWSLinkDeviceViewController.h"
 #import "UIViewController+CameraPermissions.h"
-#import "UIViewController+OWS.h"
 #import <SignalServiceKit/OWSDevice.h>
 #import <SignalServiceKit/OWSDevicesService.h>
 #import <SignalServiceKit/TSDatabaseView.h>
@@ -41,8 +40,6 @@ int const OWSLinkedDevicesTableViewControllerSectionAddDevice = 1;
     [super viewDidLoad];
     self.title = NSLocalizedString(@"LINKED_DEVICES_TITLE", @"Menu item and navbar title for the device manager");
 
-    [self useOWSBackButton];
-
     self.isExpectingMoreDevices = NO;
     self.tableView.rowHeight = UITableViewAutomaticDimension;
     self.tableView.estimatedRowHeight = 70;

Signal/src/view controllers/PrivacySettingsTableViewController.m

@@ -7,7 +7,6 @@
 #import "Environment.h"
 #import "PropertyListPreferences.h"
 #import "UIUtil.h"
-#import "UIViewController+OWS.h"
 #import "Signal-Swift.h"
 #import <25519/Curve25519.h>
 
@@ -61,8 +60,6 @@ typedef NS_ENUM(NSInteger, PrivacySettingsTableViewControllerSectionIndex) {
 
     self.title = NSLocalizedString(@"SETTINGS_PRIVACY_TITLE", @"");
 
-    [self useOWSBackButton];
-
     // CallKit opt-out
     self.enableCallKitCell = [UITableViewCell new];
     self.enableCallKitCell.textLabel.text = NSLocalizedString(@"SETTINGS_PRIVACY_CALLKIT_TITLE", @"Short table cell label");

Signal/src/view controllers/ShowGroupMembersViewController.m

@@ -8,7 +8,6 @@
 #import "Environment.h"
 #import "GroupContactsResult.h"
 #import "UIUtil.h"
-#import "UIViewController+OWS.h"
 #import <AddressBookUI/AddressBookUI.h>
 
 NS_ASSUME_NONNULL_BEGIN
@@ -59,8 +58,6 @@ static NSString *const kUnwindToMessagesViewSegue = @"UnwindToMessagesViewSegue"
 
     self.title = _thread.groupModel.groupName;
 
-    [self useOWSBackButton];
-
     [self initializeTableView];
 
     self.groupContacts =