when requestWhenInUseAuthorization() some phone not show system prompt view

when requestWhenInUseAuthorization() some phone not show system prompt view,The NSLocationWhenInUseUsageDescription key is already add. -locationManager:didChangeAuthorizationStatus: callback too kCLAuthorizationStatusNotDetermined,but the iPhone not show use location dialog,Does anyone know the reason?

when requestWhenInUseAuthorization() some phone not show system prompt view
 
 
Q