Friends lists

void DisplayFriends(List<FriendInfo> friendsCache) { friendsCache.ForEach(f => Debug.Log(f.FriendPlayFabId)); }
void DisplayPlayFabError(PlayFabError error) { Debug.Log(error.GenerateErrorReport()); }
void DisplayError(string error) { Debug.LogError(error); }

List<FriendInfo> _friends = null;

void GetFriends() {
    PlayFabClientAPI.GetFriendsList(new GetFriendsListRequest {
        IncludeSteamFriends = false,
        IncludeFacebookFriends = false,
        XboxToken = null
    }, result => {
        _friends = result.Friends;
        DisplayFriends(_friends); // triggers your UI
    }, DisplayPlayFabError);
}

enum FriendIdType { PlayFabId, Username, Email, DisplayName };

void AddFriend(FriendIdType idType, string friendId) {
    var request = new AddFriendRequest();
    switch (idType) {
        case FriendIdType.PlayFabId:
            request.FriendPlayFabId = friendId;
            break;
        case FriendIdType.Username:
            request.FriendUsername = friendId;
            break;
        case FriendIdType.Email:
            request.FriendEmail = friendId;
            break;
        case FriendIdType.DisplayName:
            request.FriendTitleDisplayName = friendId;
            break;
    }
    // Execute request and update friends when we are done
    PlayFabClientAPI.AddFriend(request, result => {
        Debug.Log("Friend added successfully!");
    }, DisplayPlayFabError);
}

// unlike AddFriend, RemoveFriend only takes a PlayFab ID
// you can get this from the FriendInfo object under FriendPlayFabId
void RemoveFriend(FriendInfo friendInfo) {
    PlayFabClientAPI.RemoveFriend(new RemoveFriendRequest {
        FriendPlayFabId = friendInfo.FriendPlayFabId
    }, result => {
        _friends.Remove(friendInfo);
    }, DisplayPlayFabError);
}

// this REPLACES the list of tags on the server
// for updates, make sure this includes the original tag list
void SetFriendTags(FriendInfo friend, List<string> newTags)
{
    // update the tags with the edited list
    PlayFabClientAPI.SetFriendTags(new SetFriendTagsRequest
    {
        FriendPlayFabId = friend.FriendPlayFabId,
        Tags = newTags
    }, tagresult => {
        // Make sure to save new tags locally. That way you do not have to hard-update friendlist
        friend.Tags = newTags;
    }, DisplayPlayFabError);
}