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@interface NUNavigationController ()

@property(nonatomic, strong) FRDLivelyButton *backBtn;

@end

@implementation KGNavigationController

- (void)pushViewController:(UIViewController *)viewController
                  animated:(BOOL)animated {
  [self.backBtn setStyle:kFRDLivelyButtonStyleCaretLeft animated:YES];

  [super pushViewController:viewController animated:animated];
  if (viewController.navigationItem.leftBarButtonItem == nil &&
      [self.viewControllers count] > 1) {
    viewController.navigationItem.leftBarButtonItems = [self custemBackItem];
  }
}

- (NSArray *)custemBackItem {
  UIBarButtonItem *btnLeft =
      [[UIBarButtonItem alloc] initWithCustomView:self.backBtn];
  UIBarButtonItem *negativeSpacer = [[UIBarButtonItem alloc]
      initWithBarButtonSystemItem:UIBarButtonSystemItemFixedSpace
                           target:nil
                           action:nil];
  // if pre iOS 7, set width to 0
  negativeSpacer.width = -15;

  return @[ negativeSpacer, btnLeft ];
}

- (FRDLivelyButton *)backBtn {
  if (!_backBtn) {
    _backBtn = [[FRDLivelyButton alloc] initWithFrame:CGRectMake(0, 0, 36, 58)];
    [_backBtn setStyle:kFRDLivelyButtonStyleCaretLeft animated:YES];
    [_backBtn setOptions:@{
      kFRDLivelyButtonLineWidth : @(1.5f),
      kFRDLivelyButtonColor : [UIColor colorWithWhite:0.282 alpha:1.000]
    }];
    _backBtn.rac_command =
        [[RACCommand alloc] initWithSignalBlock:^RACSignal * (id input) {
            [self.view endEditing:YES];
            [input setStyle:kFRDLivelyButtonStyleCaretRight animated:YES];
            [self popViewControllerAnimated:YES];
            return [RACSignal empty];
        }];
  }

  return _backBtn;
}