ios - UIAccessibilityAnnouncementNotification doesn't fire off in background mode -

i working on simple app need make post uiaccessibilityannouncementnotification when user near specific point. when app active, works fine. when press home key, stops working.

to narrow down problem, started printing in didupdateheading (since can't sit @ place, , have didupdatelocations called). saw when locked screen, heading getting updated. further, placed breakpoint on line uiaccessibilityannouncementnotification supposed fired. control arrives on line , goes next line without posting announcement.

my question: how make uiaccessibilityannouncementnotification work in lock screen? google maps app same thing. don't use voice-over announcement (such "turn left") heard in lock screen. have use speech synthesizer achieve same? sample code illustration great, beginner in ios development.

app settings: ios 8.2, iphone 4s, xcode 6.2, objective-c, app registers location updates in background mode (in .plist file)

as commented, google maps speak announcement using voiceover. you've observed appears voiceover behavior. if need perform announcement, anyway, consider using avspeechutterance api.