How to compare NSString with NSString nil Value? [duplicate] - ios

Question

This question already has answers here:
How to detect if NSString is null?
(5 answers)
Closed 8 years ago.
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");
}

Answer 1

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
}

Answer 2

You can do like this,
if ([yourString isEqual:[NSNull null]])
{
//your code goes here
}
Hope this helps.

Answer 3

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

Answer 4

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.