如何解决？
{
var extensions = new HashSet<string>();
foreach (
var ext in
Resources.Extensions.Split(new[] { Environment.NewLine, " " },
StringSplitOptions.RemoveEmptyEntries).ToList())
{
extensions.Add(ext.Trim());
}
extensions.Remove(EncryptionFileExtension);
return extensions;
}
错误CS1061：
'object' does not contain a definition for 'Split' and no extension method 'Split' accepting a first argument of type 'object' could be found (are you missing a using directive or an assembly reference?)
错误CS1061：
'TSource' does not contain a definition for 'Trim' and no extension method 'Trim' accepting a first argument of type 'TSource' could be found (are you missing a using directive or an assembly reference?)