Restore a pending invitation

This method takes no business parameters. Its success callback returns the OIMSignalingInfo that may need to be restored when the app starts:

[[OIMManager manager]
    getSignalingInvitationInfoStartAppWithOnSuccess:^(OIMSignalingInfo * _Nullable info) {
    if (info.invitation.roomID.length > 0) [self restoreIncomingCall:info];
}
    onFailure:^(NSInteger code, NSString * _Nullable message) {
    [self showCallError:code message:message ?: @"Failed to restore the call invitation"];
}];

The result may be empty, so check both info and roomID before use. This query establishes a snapshot only. After restoration, continue handling cancellation, timeout, acceptance, and hang-up delegate callbacks.