How to check if user has given camera or location permissions (android)

I really struggle with this since a while :( I need to check if the user has given the **permission to access the Android device camera** (and location on a second level). Normally the app start by asking for this permissions at launch, but if the user denies the access for the camera **I need to know and check** that later. Otherwise the user could hit the camera UI button I made and try to access the camera via webcamtexture... and that leads into a crash of the app. Since **Android API 23 you cannot ignore or already grant permissions by changing the android manifest** like I tried after reading several posts about that. Thank's to everyone who has an idea to solve this