Question

I’m storing all my data in NSUserDefaults.
Now I’m trying to store some keys with a specific prefix in an Array. Therefore, I first load the UserDefaults in a Dictionary.

NSString *myPrefix = @"prefix";
NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
NSDictionary *dict = [defaults dictionaryRepresentation];
for (NSString *keyWithPrefix in dict.keyEnumerator) {
    if ([keyWithPrefix hasPrefix: myPrefix]) {
        [relevantKeys addObject: keyWithPrefix];
    }
}

The Problem is: when I print “dict” (which represents UserDefaults). There are some keys missing.
Does NSUserDefaults delete keys, that are not needed temporarily?

Answer 1

Nope it does not, NSUserDefault is a persistance storage,
Please read the following answer it has a very good explanation
How persistent is [NSUserDefaults standardUserDefaults]?