nMobile-v1.2.1 (Build 249)

1. Fix the gray screen problem.
2. Fix the problem that the private group invites group members without vests and then invites group members with vests to fail.
3. Fix that after setting the burn after reading option in the client connection state, if the message is received from the other party after the connection is successful, the revised message after reading is sent repeatedly.
4. Fix the problem that some Samsung models failed to obtain deviceToken.
5. Fixed the problem of abnormal scanning of the QR code without the permission of the camera.