Request permissions again after user denies locati

问题:

I track the user's location and ask for permission when my load first loads using this:

locationManager.requestAlwaysAuthorization()
locationManager.startUpdatingLocation()

If the user denies, but later changes their mind by enabling the configuration option in my app, how do I ask again? For example, I have a switch for auto detecting the user's location so when they enable it, I am trying to do this:

@IBAction func gpsChanged(sender: UISwitch) {
    // Request permission for auto geolocation if applicable
    if sender.on {
        locationManager.requestAlwaysAuthorization()
        locationManager.startUpdatingLocation()
    }
}

But this code doesn't seem to do anything. I was hoping it would ask the user again if they want to allow the app to track the user's location. Is this possible?

回答1:

The OS will only ever prompt the user once. If they deny permission, that's it. What you can do is direct the user to the Settings for your app by passing UIApplicationOpenSettingsURLString to UIApplication's openURL: method. From there, they can re-enable location services if they wish. That said, you probably shouldn't be too aggressive about bugging them for the permission.

回答2:

The permission pop up only shows once. So we have to redirect users to Settings after that. Here comes the code in Swift:

 @IBAction func userDidClickButton(_ sender: Any) {

    // initialise a pop up for using later
    let alertController = UIAlertController(title: "TITLE", message: "Please go to Settings and turn on the permissions", preferredStyle: .alert)
    let settingsAction = UIAlertAction(title: "Settings", style: .default) { (_) -> Void in
        guard let settingsUrl = URL(string: UIApplicationOpenSettingsURLString) else {
            return
        }
        if UIApplication.shared.canOpenURL(settingsUrl) {
            UIApplication.shared.open(settingsUrl, completionHandler: { (success) in }
         }
    }
    let cancelAction = UIAlertAction(title: "Cancel", style: .default, handler: nil)
    alertController.addAction(cancelAction)
    alertController.addAction(settingsAction)

    // check the permission status
    switch(CLLocationManager.authorizationStatus()) {
        case .authorizedAlways, .authorizedWhenInUse:
            print("Authorize.")
            // get the user location
        case .notDetermined, .restricted, .denied:
            // redirect the users to settings
            self.present(alertController, animated: true, completion: nil)
    }
}

回答3:

You only get one chance. For the user to enable permissions after denying them, they have to go through the Settings app. See Requesting Permission to Use Location Services in CLLocationManager.

回答4:

You can have an alternate solution!! You can show your own alert with the better message which can convince your user to allow to receive push notifications for your app. If user allows, then only you show default permission alert for enable push notification otherwise if user disallows, don't show default alert in-fact, you can save corresponding flag in your database or NSUserDefaults and can ask user later on again and again on some events in your app.