/// <summary>
/// 登录
/// </summary>
/// <param name="user_id">用户的 UserID</param>
/// <param name="user_sig">用户的 UserSig</param>
/// <param name="handler">登录成功与否的回调。回调函数定义请参考 TIMCommCallback</param>
public static TIMResult IMLogin(string user_id, string user_sig, LoginResultDelegate handler = null)
{
var ptr = DelegateConverter.ConvertToIntPtr(handler);
return((TIMResult)TIMClientAPIDef.TIMLogin(user_id, user_sig, LoginResultCallBack, ptr));
}