How to compare NSString with NSString nil Value?

Question

I'm new to iOS development. I get an error when I compare NSString with NSString nil value. It is not working in if condition.

my code is:

  NSDictionary *responseFromJSON = [JSON objectForKey:@"response"];
  NSString *strResponseMsg = [responseFromJSON objectForKey:@"104"];   
  if ([strResponseMsg isEqualToString:nil])
     {
         NSLog(@"login Invalid");
     }
     else
     {
         NSLog(@"login success");
     }

Its solve thanks -rajeev – Bhavdip Patel Jan 19 '15 at 06:33 — Bhavdip Patel, Jan 19 '15 at 06:33
no mention @bhavdip patel – Code cracker Jan 19 '15 at 06:45 — Code cracker, Jan 19 '15 at 06:45

score 1 · Answer 1 · answered Jan 19 '15 at 06:36

You can simply do like this,

    NSString * string = nil;
if (string!=nil &&  // not nil, means 0x0 object
    string.length>0 && // at leaset one character should exists
    [string isEqual:[NSNull null]]) { // to avoid 'null' in string

    // valid string
}

score 0 · Answer 2 · answered Jan 19 '15 at 06:33

0

You can do like this,

if ([yourString isEqual:[NSNull null]])
{
  //your code goes here
}

Hope this helps.

answered Jan 19 '15 at 06:33

iOSNoob

1,420
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score 0 · Answer 3 · answered Jan 19 '15 at 06:41

0

Use below

NSString *strResponseMsg = [responseFromJSON objectForKey:@"104"];   
if (!strResponseMsg)
{
    NSLog(@"login Invalid");
}
else
{
    NSLog(@"login success");
}

answered Jan 19 '15 at 06:41

Tapas Pal

6,877
6
37
82

score 0 · Answer 4 · answered Jan 19 '15 at 06:44

If you want to check the NSString whether it's nil or empty. You just need to do something like that:

if (strResponseMsg.length) {}

Because it will not go inside if the strResponseMsg is nil or empty. It will only go inside when strResponseMsg is not nil and no empty.

How to compare NSString with NSString nil Value?

4 Answers4