iOS Swift4 Didn't Ask for Permission on App

Question

I need access to CMAltimeter in my App. So of course I need to ask for permission. And I add the Privacy - Location When In Use Usage Description and of course Privacy - Motion Usage Description with an Value in info.plist but the App never asks for Permission and the Authorization Status is always not determined

(Device -> iPhone XR iOS12) and newest Xcode. My Signing in Xcode is only Personal Team with my Apple ID because we only need this for the university. (And till this day I haven't buy the Developer License) The App and CoreMotion runs. (CMDeviceMotion doesn't need permissions)

func myDeviceMotionQFE(){
    if CMAltimeter.isRelativeAltitudeAvailable() {
        switch CMAltimeter.authorizationStatus() {
        case .notDetermined:
            print("Altimeter -> NotDetermined")
            break
        case .denied:
            print("Altimeter -> Denied")
            break
        case .restricted:
            print("Altimeter -> Restricted")
            break
        case .authorized:
            print("Altimeter -> Authorized")
}

Did you have the line `locationManager.requestWhenInUseAuthorization()` in your code? — qtngo, Mar 08 '19 at 14:10
Okay the prompt for Location is coming (So I am one step further because before there were no prompt), but I need the prompt for the Altimeter which is in CoreMotion not CoreLocation. — Robin M., Mar 10 '19 at 09:07

score 1 · Accepted Answer · edited Apr 21 '19 at 04:22

My initial problem was that startRelativeAltitudeUpdates(to:withHandler) did not work and was sidetracked by exactly the same problem: CMAltimeter.authorizationStatus() was always .notDetermined.

However it turned out that that CMAltimeter instance got out of scope and was automatically ARC'ed and the handler not called any more.

Summary: There is no requestAuthorization() for CMAltimeter in IOS12, neither one is needed.

score -1 · Answer 2 · answered Mar 08 '19 at 23:11

Welcome! You need to do two things to get permission for altimetry data. First is the plist description that you already have. The second is to call CMAltimeter.authorizationStatus(). This will ask the user for permission using the string you have in the plist.

You can get one of four results as in CMAltimeter CMAuthorizationStatus: notDetermined, restricted, denied, or authorized. If you get authorized, you're good to go. If you get denied the user hasn't given their permission. Restricted is that there's some system-wide restriction on this location data (might be from MDM perhaps).

Search in your Xcode documentation for CMAltimeter, authorizationStatus, and CMAuthorizationStatus.

When you get "authorized" response, you can call startRelativeAltitudeUdpates with a handler and your app will get the updates when data is available.

I've edit my Question, because I have already CMAltimeter.authorizationStatus() and checking for the 4 Enums. But I never get the prompt and the switch always goes in the .notDetermined Case — Robin M., Mar 10 '19 at 09:02

iOS Swift4 Didn't Ask for Permission on App

2 Answers2