public async static Task <ObservableCollection <RegionTypeModel> > GetCityList(string campaignId) { try { var cities = new List <List <RegionTypeModel> >(); var campaigns = campaignId.Split(','); foreach (var campaign in campaigns) { var cityInfo = await TrackService.GetCityInfo(campaign); if (cityInfo == null) { continue; } cities.Add(cityInfo); } var list = EraseDuplacatedCity(cities); return(new ObservableCollection <RegionTypeModel>(list)); } catch (Exception ex) { ShowMessage.Show("获取城市列表出错"); LogHelper.LogMessage(MethodBase.GetCurrentMethod().DeclaringType, LogHelper.LogLevel, "Failed to GetTableSource", ex); } return(new ObservableCollection <RegionTypeModel>()); }