My app was working smoothly in iOS 10 but not as i updated the application to iOS 11, application started to crash. And I am getting following error:
This app has crashed because it attempted to access privacy-sensitive data without a usage description. The app's Info.plist must contain an NSContactsUsageDescription key with a string value explaining to the user how the app uses this data.
As your error is suggesting just add
"Privacy - Contacts Usage Description"
into your info.plist. It will be of String type so add whatever popup message you want to show to the user asking for accessing his/her contact list. Eg. you may write "Application wants to access your contacts list."
Key will be "Privacy - Contacts Usage Description"
and
Value will be "Application wants to access your contacts list."