NSJSONSerialization returns "" string

Question

I'm try to set an NSDictionary to a JSON object retrieved from the server, I'm doing that in this line:

_peopleArray = [NSJSONSerialization JSONObjectWithData:data options:0 error:nil];

It works fine and properly creates the dictionary. However, I have a problem, values that are null in the JSON object are stored as "<null>" string values in the dictionary. Is there any way to fix this or work around it? I want to avoid traversing through the entire thing and setting them to @"".

Thanks for any help!

~Carpetfizz

score 10 · Answer 1 · edited Jan 19 '15 at 17:38

10

You are wrong. null values in JSON are not stored as <null> string values. They are stored as NSNull objects, which NSLog logs as <null>.

You can never trust what data you were given. If you assume you got an NSString and the server sends you a number, your code is likely to crash.

NSString* myJSONString = ...;
if ([myJSONString isKindOfClass:[NSString class]]) {
    it is a string
} else {
    it is not a string
}

edited Jan 19 '15 at 17:38

Martin R

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answered Jan 19 '15 at 11:50

gnasher729

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(adding a bit of extra info) Not only do they NSLog as a string, but also `[NSString stringWithFormat:@"%@",nullObj];` will output '' in your app, which is why most people are misled by debugging this dataType. – Chris J May 05 '16 at 22:27

score 1 · Accepted Answer · answered Jun 25 '14 at 05:31

There is nothing I guess, though it can be easily corrected from api makers, if not possible, you can always put a simple macro, I use to avoid such thing, follow macro below

#define Is_Empty(value) (value == (id)[NSNull null] || value == nil || ([value isKindOfClass:[NSString class]] && ([value isEqualToString:@""] ||  [value isEqualToString:@"<null>"]))) ? YES : NO

#define IfNULL(original, replacement) IsNULL(original) ? replacement : original

#define IsNULL(original) original == (id)[NSNull null]

#define SafeString(value) IfNULL(value, @"")

Usage

self.label.text=SafeString([dic objectForKey:@"name"]);

NSJSONSerialization returns "" string

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