无法将类（Swift）用于目标C

我正在做苹果文档中写的相同步骤。但是我无法在目标c文件中访问swift类。

代码：

斯威夫特文件

import Foundation
import UIKit
@objc class checkk : UIViewController {
    func alertView ()
    {
        let al = UIAlertView(title: "HeLLo", message: "Working", delegate: nil, cancelButtonTitle: "OK", otherButtonTitles: "ww", "sdd")

        al.show()

    }
}

目标C文件

#import "ViewController.h"

#import "SwiftIntoObjectiveC-Bridging-Header.h"  // automatically generated by Xcode. Nothing is written in this.

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];

     checkk *ck =[checkk new];  // error : use of undeclared identifier check.

    // Do any additional setup after loading the view, typically from a nib.
}

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];

    // Dispose of any resources that can be recreated.
}

- (IBAction)Click:(id)sender {

}
@end

错误：使用未声明的标识符检查。