Check if NSDictionary is empty

Question

I want to check if an NSDictionary is empty. I am doing it like this.

  mutDictValues = [[[NSUserDefaults standardUserDefaults] objectForKey:@"dicValues"]mutableCopy];
    NSLog(@"dictValues are %@",mutDictValues);
    if(mutDictValues == NULL){
        arrCities = [[NSMutableArray alloc]init];
        NSLog(@"no cities seleceted");
    }else{
          arrCities = [[NSMutableArray alloc]init];
          arrCities = [mutDictValues objectForKey:@"cities"];
          [self placeCities];
    }

But it alwasy crashes on this line arrCities = [mutDictValues objectForKey:@"cities"]; with the following error:

-[__NSCFConstantString objectForKey:]:

Can someone help me with this ?

if (![dictTemp isKindOfClass:[NSDictionary class]]) { // do something DisplayAlert(@"No data found") } — kb920, Jul 19 '13 at 13:00

Balu · Accepted Answer · 2013-07-19T11:56:38.083

25

While retrieving the dictionary values from NSUserDefaults that dictionary automatically converted into string that is the reason for getting crashed and for checking dictionary use
[dictionary count];

EDIT:- use dictionaryForKey: method

NSDictionary *dict =[[NSDictionary alloc]initWithObjectsAndKeys:@"hi",@"one",nil];
[[NSUserDefaults standardUserDefaults] setObject:dict forKey:@"dic"];
NSDictionary *dictn = [[NSUserDefaults standardUserDefaults] dictionaryForKey:@"dic"];
NSLog(@"%@",[dictn objectForKey:@"one"]);

edited Jul 19 '13 at 11:56

answered Jul 19 '13 at 11:49

Balu

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Is it possible to get this back as NSDictionary ? – Steaphann Jul 19 '13 at 11:51
once check this one,http://stackoverflow.com/questions/6797096/delete-all-keys-from-a-nsuserdefaults-dictionary-iphone – Balu Jul 19 '13 at 11:51
if (![dictTemp isKindOfClass:[NSDictionary class]]) { // do something DisplayAlert(@"No data found") } – kb920 Jul 19 '13 at 12:58

score 8 · Answer 2 · edited Dec 09 '15 at 17:08

8

if ( [mutDictValues count] == 0 ) {
    //code here
}
else {
    //code here
}

After having your dic retrieved this should do

edited Dec 09 '15 at 17:08

itsji10dra

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answered Jul 19 '13 at 12:39

rashii

512
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17

score 2 · Answer 3 · answered Jul 19 '13 at 11:47

2

try this,

if([myDict count] > 0)
    NSLog(@"Dictionary is not empty");
else
    NSLog(@"Dictionary is empty");

answered Jul 19 '13 at 11:47

βhargavḯ

9,694
1
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score 1 · Answer 4 · edited Jul 19 '13 at 12:07

1

BOOL containsKeyABC = [myDict: valueForKey:@"ABC"];

int items = dict.count;

if (items > 0) {
     //not empty
}

edited Jul 19 '13 at 12:07

Abdullah Shafique

6,850
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answered Jul 19 '13 at 11:47

William Falcon

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109

score 1 · Answer 5 · answered Jul 19 '13 at 11:49

1

Somewhere you treat a nsstring (a concrete subclass) as NSdictionary.

answered Jul 19 '13 at 11:49

vikingosegundo

51,574
14
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score 1 · Answer 6 · answered Jan 05 '15 at 06:16

I had a bit different issue but it is related so i would like to share it here.

I was fetching the webservices & storing data in NSDictionary & again Fetching objectForKey which was Null. So the solution i found is as under

NSMutableDictionary *result = [NSJSONSerialization JSONObjectWithData:[str dataUsingEncoding:NSUTF8StringEncoding] options:0 error:nil];

    // NSLog(@"%@" , result);

    NSMutableDictionary *sup = [result objectForKey:@"keysupplied"];
    NSNull *n=[NSNull null];
    if ( sup ! = n ){
      //Your code if its not null
    }

The reason behind using NSNull was it was returning (NSNull *) when i debugged the application So i finally figured out this way.

score 0 · Answer 7 · edited May 23 '17 at 10:31

As most of the answers have correctly pointed out that you are passing un-recognized selector objectForKey: to a NSString instance instead of NSDictionary, hence observing exception

-[__NSCFConstantString objectForKey:]:

Check NSUserDefaults to see whether cities returns a dictionary or something else. You can do this by two ways

I. NSLog all data in NSUserDefaults

NSLog(@"%@", [[NSUserDefaults standardUserDefaults] dictionaryRepresentation]);

II. Check the plist file which store the NSUserDefaults from the Application folder. Check this answer for more details.

Hope that helps.

score 0 · Answer 8 · answered Sep 30 '14 at 11:00

0

try this code

NSMutableDictionary *dict = ...

BOOL isEmpty = ([dict count] == 0);

answered Sep 30 '14 at 11:00

Waseem Shah

2,209
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score 0 · Answer 9 · answered Dec 17 '21 at 10:27

0

if (myDict.count)
    NSLog(@"Dictionary is not empty");
else
    NSLog(@"Dictionary is empty");

Every number that is 0 equals to @NO.

Every number that is not 0 equals to @YES.

Therefore you can just pass the count into the if.

answered Dec 17 '21 at 10:27

Redwolf

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Check if NSDictionary is empty

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