How to Verify device token before sending a push notification in ios?

I am sending a bulk push notification in ios. But sometimes in 100 device token some device token is invalid.so when an apns server gets invalid device token server stop sending push.

Please help me resolve this issue.

try validating your token by sending silent pushes using a webjob. Run the webjob everynight. If sending response is 400BadDeviceToken, consider the token invalid.