openParentApplication仅在应用程序在前台运行时才有效 [英] openParentApplication only works when the app is running in the foreground

问题描述

我正在尝试使用 openParentApplication 从服务器请求数据并在监视扩展中使用它，但是当主应用程序是没有在前台运行。当主应用程序在前台运行时，一切正常。

I'm trying to request data from the server by using openParentApplication and use it in the watch extension, but I don't get anything back when the main app is not running in the foreground. When the main app is running in the foreground everything works fine.

推荐答案

之前我遇到过这个问题，原因是你没有注册长时间运行的后台操作，系统将其终止。
这是我对此进行排序的方法，请参阅注解说明，这些都在AppDelegate文件中，并且在swift中，但您可以轻松将其移植到Objective-c：

I had this issue before and the reason was that you haven't registered long running background operation and the system kill it. This is how I sorted this, please see comments for explanations, this is all in AppDelegate file and it in swift but you can easily port it to Objective-c:

private var backgroundTask: UIBackgroundTaskIdentifier = UIBackgroundTaskInvalid

func registerBackgroundTask() {
        backgroundTask = UIApplication.sharedApplication().beginBackgroundTaskWithExpirationHandler {
            [unowned self] in
            self.endBackgroundTask()
        }
        assert(backgroundTask != UIBackgroundTaskInvalid)
    }

func endBackgroundTask() {
    UIApplication.sharedApplication().endBackgroundTask(backgroundTask)
    backgroundTask = UIBackgroundTaskInvalid
}

// MARK: - Watch Kit
func application(application: UIApplication, handleWatchKitExtensionRequest userInfo: [NSObject : AnyObject]?, reply: (([NSObject : AnyObject]!) -> Void)!) {

    registerBackgroundTask()

    // Fetch the data from the network here
    // In the competition handler you need to call:
    // the nil can be replaced with something else you want to pass back to the watch kit
    reply(nil)
    if self.backgroundTask != UIBackgroundTaskInvalid {
        self.endBackgroundTask()
    }
}

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