2019更新

从watchOS 6.0开始，可以创建在手表上运行的应用程序，而无需在配对的iOS设备上安装相应的应用程序.

As of watchOS 6.0 it is possible to create apps that run on the watch without the need to install a corresponding app on the paired iOS device.

您可以按照 Apple的说明将现有的手表应用转换为独立的手表应用程序，或仅在Xcode中创建一个新的独立手表应用程序.

You can follow Apple's instructions to convert an existing watch app into an independent watch app, or just create a new stand-alone watch app in Xcode.

App Store Connect流程基本上相同-创建一个iOS应用程序.您无需提供任何iOS应用程序屏幕截图，只需观看屏幕截图即可.

The App Store Connect process is still essentially the same - Create an iOS app. You do not need to provide any iOS app screenshots, only watch screen shots.

原始答案

Apple Watch应用程序作为iOS扩展作为一个iOS应用程序托管在iOS应用程序中-因此，要提交Apple Watch应用程序，您需要提交一个iOS应用程序.

Apple Watch apps are hosted inside an iOS app, as an iOS extension - so to submit an Apple Watch app you need to submit an iOS app.

来自 Apple Watch编程指南

Apple Watch需要使用iPhone才能运行第三方应用.要创建第三方应用，您需要两个单独的捆绑包:WatchKit应用程序(在Apple Watch上运行)和WatchKit扩展程序(在用户的iPhone上运行).WatchKit应用仅包含与您的应用程序用户关联的情节提要和资源文件界面.WatchKit扩展包含用于管理WatchKit应用程序的用户界面，用于响应用户交互.

Apple Watch requires the presence of an iPhone to run third-party apps. To create a third-party app, you need two separate bundles: a WatchKit app (that runs on Apple Watch) and a WatchKit extension (that runs on the user’s iPhone). The WatchKit app contains only the storyboards and resource files associated with your app’s user interface. The WatchKit extension contains the code for managing the WatchKit app’s user interface and for responding to user interactions.

由于WatchKit应用程序扩展了现有iOS应用程序的行为，因此WatchKit应用程序和WatchKit扩展程序捆绑在一起并打包在iOS应用程序捆绑包中.在安装iOS应用程序期间，如果存在配对的Apple Watch，系统会提示用户安装WatchKit应用程序.

Because a WatchKit app extends the behavior of your existing iOS app, the WatchKit app and WatchKit extension are bundled together and packaged inside your iOS app bundle. During installation of your iOS app, the system prompts the user to install the WatchKit app when a paired Apple Watch is present.

将托管的iOS应用提交到App Store时，您可以选择提供Apple Watch应用的屏幕截图以及主应用的屏幕截图.

When you submit your hosting iOS app to App Store you have an option to provide Apple Watch application screen shots to go along with your main app screenshots.