public static async Task <List <City> > GetCitys()
        {
            SQLiteDB db = new SQLiteDB();

            if (!db.Database.CanConnect())
            {
                Tool.WriteLog("错误", "数据库无法连接");
                return(new List <City>());
            }
            List <City> cities = await db.Citys.ToListAsync();

            if (cities != null && cities.Count > 0)
            {
                return(cities);
            }
            cities = new List <City>
            {
                new City()
                {
                    ID              = 1,
                    CityName        = "十堰",
                    CityEnglishName = "ShiYan"
                },
                new City()
                {
                    ID              = 2,
                    CityName        = "武汉",
                    CityEnglishName = "WuHan"
                },
                new City()
                {
                    ID              = 3,
                    CityName        = "南京",
                    CityEnglishName = "NanJing"
                },
                new City()
                {
                    ID              = 4,
                    CityName        = "杭州",
                    CityEnglishName = "HangZhou"
                },
                new City()
                {
                    ID              = 5,
                    CityName        = "成都",
                    CityEnglishName = "ChengDu"
                },
                new City()
                {
                    ID              = 6,
                    CityName        = "无锡",
                    CityEnglishName = "WuXi"
                }, new City()
                {
                    ID              = 7,
                    CityName        = "广州",
                    CityEnglishName = "GuangZhou"
                }, new City()
                {
                    ID              = 8,
                    CityName        = "海口",
                    CityEnglishName = "HaiKou"
                }, new City()
                {
                    ID              = 9,
                    CityName        = "南宁",
                    CityEnglishName = "NanNing"
                }, new City()
                {
                    ID              = 10,
                    CityName        = "拉萨",
                    CityEnglishName = "LaSa"
                }
            };
            db.AddRange(cities);
            int rows = await db.SaveChangesAsync();

            if (rows == cities.Count)
            {
                return(cities);
            }
            return(new List <City>());
        }