Retrieving values from NSUserDefault - error

Question

I am trying to retrieve a value from a NSUserDefaults. When I retrieve the value I get a (null), which is fine.

How can I validate it ?

NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
if ([defaults objectForKey:@"Value"] !=[NSNull null] ) {
   NSlog(@"returns a value");
} else NSlog(@"return a null");

However, even though I get a null it doesn't get detected (It goes in to the if block). How can i sort this?

`NSNull`, or `[NSNull null]` is a class reference. So checking `!= [NSNull null]` would be checking it against the class `NSNull`. — CaptJak, Feb 10 '16 at 18:33

Eiko · Answer 1 · 2016-02-10T18:17:16.807

2

nil is not the same as [NSNull null]. Just check with value != nil.

nil is (simplified) 0. [NSNull null] is a real object.

edited Feb 10 '16 at 18:17

answered Feb 10 '16 at 18:08

Eiko

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Sorry, meant nil. I've done to much c++ lately with nullptr. :) – Eiko Feb 10 '16 at 18:17

Mihado · Accepted Answer · 2016-02-10T18:14:55.840

1

NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
 if ([defaults objectForKey:@"Value"] != nil) {
     NSlog(@"returns a value");
 } else {
    NSlog(@"return a nil");
 }

This will work. And what Eiko said is right.

edited Feb 10 '16 at 18:14

answered Feb 10 '16 at 18:12

Mihado

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It says: `use of undeclared identifier 'null'` – Illep Feb 10 '16 at 18:14
Because it is nil...Not null. – Whirlwind Feb 10 '16 at 18:14
My apologies, I made a mistake – Mihado Feb 10 '16 at 18:14

Retrieving values from NSUserDefault - error

2 Answers2