Add New Item To NSDictionary Doesn't Work

Question

I use Xamarin.ios with the below code:

var dict = NSUserDefaults.StandardUserDefaults.DictionaryForKey("TheDictKey");
if (dict == null)
{
    dict = new NSDictionary();
    NSUserDefaults.StandardUserDefaults.SetValueForKey(dict,(NSString)"TheDictKey");
}
dateTime = dateTime.ToUniversalTime();
dict[(NSString)"ValueKey"] = new NSString("Value"); //<------ throw exception here

The last sentence alway throw exception "NotSupported".

How can I update the dictionary? Thanks

Answer 1

That is because NSDictionary is immutable. That means that after it is created, you cannot change it. Use NSMutableDictionary for this purpose instead, which is a subclass of NSDictionary.

From Apple's NSDictionary reference:

NSDictionary creates static dictionaries, and NSMutableDictionary creates dynamic dictionaries.

Here: click