Remove NSUserDefaults for keys starting with

Question

I want to remove strings that are stored in the NSUserDefaults for the keys beginning with "NavView".
I thought about using the hasPrefix() method, but I just can't seem to figure it out.

I know that other programming languages have features like taking every string with a certain beginning by passing the prefix they want it to have like: find all strings with "NavView*" or something. (using signs like the star to indicate that)

Any ideas how I could do that except storing all the objects in an array and saving that?
Thanks in advance!

Muzahid · Accepted Answer · 2019-03-02T09:25:08.330

15

UserDefaults is one kind of key value pair persistent store. To solve your problem you have to follow the steps:

Iterate over the all keys of UserDefaults Dictionary.
Check each key has prefix "NavView".
If key has the prefix then remove the object for the key.

Swift 4:

for key in UserDefaults.standard.dictionaryRepresentation().keys {
    if key.hasPrefix("NavView"){
        UserDefaults.standard.removeObject(forKey: key)
    }
}

Objective C :

NSUserDefaults *userDef = [NSUserDefaults standardUserDefaults];

for (NSString *key in [userDef dictionaryRepresentation].allKeys) {
    if ([key hasPrefix:@"start"]) {
        [userDef removeObjectForKey:key];
    }
}

edited Mar 02 '19 at 09:25

answered Mar 20 '16 at 07:44

Muzahid

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This looks promising. I didn't know about the `.keys`. I will try that, thanks already. – LinusGeffarth Mar 20 '16 at 07:46
Thats my pleasure :) – Muzahid Mar 21 '16 at 01:13

score 1 · Answer 2 · answered Oct 11 '19 at 01:08

1

Swift 5 is the same as Swift 4

for key in UserDefaults.standard.dictionaryRepresentation().keys {
            if key.hasPrefix("NavView") {
                UserDefaults.standard.removeObject(forKey: key)
            }
        }

answered Oct 11 '19 at 01:08

Zgpeace

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score 0 · Answer 3 · edited May 23 '17 at 12:00

0

You can get all the keys and filter only the ones that start with the prefix. See example - Delete all my NSUserDefaults that start with a certain word

edited May 23 '17 at 12:00

Community

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answered Mar 20 '16 at 07:14

little

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Remove NSUserDefaults for keys starting with

3 Answers3