添加UIBarButtonItem但它不会显示在接口上

Question

我正在尝试以编程方式向viewController添加一个返回按钮，但它不会通过模拟器显示在界面上。我在代码中遗漏了什么？只有空白屏幕存在构建错误！

#import "ViewController.h"

@interface ViewController ()
@end

@implementation ViewController
- (void) performAdd:(id)paramSender{
   NSLog(@"Button got called");
}

- (void)viewDidLoad
{
    [super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.

    self.view.backgroundColor = [UIColor blackColor];
    self.title =@"go Back";

    self.navigationItem.rightBarButtonItem = [[UIBarButtonItem alloc]
     initWithBarButtonSystemItem:(UIBarButtonSystemItemAdd)
     target:self
     action:@selector(performAdd:)];
}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}
@end