Is this string null or not

Question

This is the output of my string in console.

device type-------------(
mobile,
"<null>",
tablet

How to deal with the 2nd value. I tried the following way, but doesn't work app gets kill here on these lines.

if([dType isEqualToString:@"<null>"])
if([dType isEqualToString:@""])
if([dType isEqualToString:@"null"])

None of the above work. Please guide for the above. Thanks in advance.

On my first google hit I found: http://stackoverflow.com/questions/482276/how-can-i-test-an-nsstring-for-being-nil And http://stackoverflow.com/questions/2401234/objective-c-how-to-check-if-a-string-is-null — rptwsthi, Feb 13 '13 at 05:21

score 1 · Accepted Answer · edited Feb 13 '13 at 05:41

1

 if (dType == (NSString *)[NSNull null])
    {
       // your logic here
    }

edited Feb 13 '13 at 05:41

Jerry Coffin

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answered Feb 13 '13 at 05:23

Rushabh

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score 0 · Answer 2 · edited May 23 '17 at 12:06

0

Instead of comparing the string. It's always advisable you check the length of string. Like :

[yourString length] == 0

And, check the condition. You can also check this. Hope this help.

edited May 23 '17 at 12:06

Community

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answered Feb 13 '13 at 05:12

Rushi

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it is giving error this way. -[NSNull length]: unrecognized selector sent to instance 0x1e6678. – iPhone Programmatically Feb 13 '13 at 05:26
@iPhone : [NSNull length]: this is wrong. You have to send your string here. For eg [yourStrin length] == 0 if it equals to 0, that means it's a null,nil or "" string. – Rushi Feb 13 '13 at 05:28

score 0 · Answer 3 · edited Feb 13 '13 at 05:19

0

You can check if [string length] == 0. This will check if it's a valid but empty string (@"") as well as if its nil, since calling length on nil will also return 0.

Alternatively, you can try with [string isEqual:[NSNull null]]; also

edited Feb 13 '13 at 05:19

Ajay Sharma

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answered Feb 13 '13 at 05:12

Vikas S Singh

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score 0 · Answer 4 · answered Feb 13 '13 at 05:15

0

I use two macros for this its in my Defines.h file

#define NULLVALUE(m)                    (m == nil ? @"" : m)
#define NULLVALUE1(m)                    (m == nil ? @" " : m)

It changes null value to "" or space " " easy to handle.

answered Feb 13 '13 at 05:15

amar

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score 0 · Answer 5 · answered Feb 13 '13 at 05:33

0

you can check that like this

if ([YOUR_STRING isKindOfClass:[NSNull class]] || YOUR_STRING == nil ) {

}

answered Feb 13 '13 at 05:33

SachinVsSachin

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score 0 · Answer 6 · answered Feb 13 '13 at 05:52

+(NSString *) removeNull:(NSString *) string {

    if ([string isEqual:[NSNull null]] ) {
        return @"";
    }

    if ([string isEqualToString:@"<null>"]) {
        return @"";
    }
    if ([string isEqualToString:@"null"]) {
        return @"";
    }
    @try {
        NSRange range = [string rangeOfString:@"null"];
        ////////NSLog(@"in removeNull : %d  >>>> %@",range.length, string);
        if (range.length > 0 || string == nil) {
            string = @"";
        }
        range = [string rangeOfString:@"<null>"];
        ////////NSLog(@"in removeNull : %d  >>>> %@",range.length, string);
        if (range.length > 0 || string == nil) {
            string = @"";
        }
    }
    @catch (NSException *exception) {
        return @"";
    }
    @finally {

    }


    string = [self trimString:string];
    return string;
}

------------------------------ call like this NSString *strFb = [classname removeNull:YourString];

Is this string null or not

6 Answers6