iOS7：UIBarButtonItem上的选择器没有执行该方法

Question

我是iOS新手。我的应用程序有多个视图控制器，因此我将代码抽象为

NavigationBar.h

@interface NavigationBar : NSObject
- (void) title: (NSString *) title withViewController: (UIViewController *) viewController;
@end

NavigationBar.m

#import "NavigationBar.h"
#import "PennyNavigationController.h"


@implementation NavigationBar
- (void)title:(NSString *)title withViewController:(UIViewController *)viewController {
    viewController.title = title;
    viewController.navigationItem.leftBarButtonItem = [[UIBarButtonItem alloc] initWithTitle:@"Menu"
                                                                                       style:UIBarButtonItemStyleBordered
                                                                                      target:(PennyNavigationController *) viewController.navigationController
                                                                                      action:@selector(showMenu)];
    viewController.navigationItem.rightBarButtonItem = [[UIBarButtonItem alloc] initWithImage:[self getImageNamed:@"Add" withDimension:30] style:UIBarButtonItemStylePlain target:self action:@selector(sayHello:)];

}

- (IBAction)sayHello:(id)sender
{
    NSLog(@"add new transaction");
}

- (void)btnClicked:(id)sender {
//    NSLog(@"add new transaction");
}

当应用程序启动时，我点击Add图片，我看不到日志，另外我看到该应用程序关闭。

我做错了什么？

P.S：似乎我在Add a custom selector to a UIBarButtonItem中完全提到过，但它仍然不起作用