ios - `@objc(ViewController) ` 是做什么的？

Question

我有这个快速代码:

func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject : AnyObject]?) -> Bool {
...
    let storyboard = UIStoryboard(name: "Main", bundle: nil)
        let controller = storyboard.instantiateInitialViewController()!
        if (controller is InlineMainViewController ){
            mainViewController = controller as! InlineMainViewController
        }
        window?.rootViewController = controller
        window?.makeKeyAndVisible()
}

当我的 viewController 具有此属性时:

@objc(ViewController)  // match the ObjC symbol name inside Storyboard
public class InlineMainViewController: UIViewController, 

( Controller 是 InlineMainViewController ) 返回 false

当它没有此属性时:

public class InlineMainViewController: UIViewController, 

( Controller 是 InlineMainViewController ) 返回 true

我的Main.sotryboard已连接到InlineMainViewController

我从 Google Analytics github 示例中获取了 @objc(ViewController)

Answer 1

来自Swift Type Compatibility

You can use the @objc attribute if your Swift class doesn’t inherit from an Objective-C class, or if you want to change the name of a symbol in your interface as it’s exposed to Objective-C code.

这段代码:

@objc(ViewController)

当通过生成的 header 将其导入到 Objective-C 代码中时，将导致此属性后面的类具有括号中的名称，如 Importing Swift into Objective-C 中所述。

To import Swift code into Objective-C from the same target

• Import the Swift code from that target into any Objective-C .m file within that target using this syntax and substituting the appropriate name:

  #import "ProductModuleName-Swift.h"