以编程方式将UIBarButtonItem目标设置为以前的视图控制器

// Swift语言示例
let backButton = UIBarButtonItem(title: "返回", style: .plain, target: self, action: #selector(backButtonTapped))
navigationItem.leftBarButtonItem = backButton

@objc func backButtonTapped() {
    navigationController?.popViewController(animated: true)
}

// Objective-C语言示例
UIBarButtonItem *backButton = [[UIBarButtonItem alloc] initWithTitle:@"返回" style:UIBarButtonItemStylePlain target:self action:@selector(backButtonTapped)];
self.navigationItem.leftBarButtonItem = backButton;

- (void)backButtonTapped {
    [self.navigationController popViewControllerAnimated:YES];
}