How to check if an object is nil in Objective-C?

Question

So I know this seems pretty basic but it doesn't seem to be working for some reason. I have the following code.

Target *t = self.skill.target;


if (![t isEqual:nil]) {
    NSLog(@"Not nil");
}

I tried this and it comes up as not nil everytime which is great except for when t should actually be nil. I even tried putting variation into the code like so and my t is still coming up as not nil for some reason. Am I doing something wrong? :\

Target *t = self.skill.target;
t = nil;

if (![t isEqual:nil]) {
    NSLog(@"Not nil");
}

that is not really possible scenario, you probably misinterpret something seriously. — holex, Mar 05 '15 at 08:36
You can check my answer https://stackoverflow.com/a/51626469/3378413 — Mihir Oza, Aug 01 '18 at 06:15
Looking at the answers, I'm thinking if the value can be revealed through the debugger, too. Am I getting this wrong or are both ways legit? — Ali, May 14 '20 at 09:55

score 27 · Accepted Answer · answered Mar 04 '15 at 11:00

You can do it normally just by checking the object itself. There is also a good explanation on NSHipster for NSNull.

if( myObject ){
    // do something if object isn't nil
} else {
    // initialize object and do something
}

otherwise just use

if( myObject == nil ){

}

score 1 · Answer 2 · answered Mar 04 '15 at 11:00

1

Target *t = self.skill.target;
t = nil;

if (t) {
    NSLog(@"t is Not nil");
}
if (!t) {
    NSLog(@"t is nil");
}

answered Mar 04 '15 at 11:00

Saif

2,678
2
22
38

score 1 · Answer 3 · edited May 23 '17 at 12:33

1

As this answer says:

Any message to nil will return a result which is the equivalent to 0 for the type requested. Since the 0 for a boolean is NO, that is the result.

So, a nil object is special. you can't compare it using the isEqual method. you should compare it without sending it a message, like this:

if (t) 
{
}

or simply:

if (t != nil)
{
}

edited May 23 '17 at 12:33

Community

1
1

answered Mar 04 '15 at 11:00

Tomer

3,149
23
26

score 0 · Answer 4 · answered Mar 04 '15 at 11:00

0

The if operation checks nillable so this should works:

Target *t = self.skill.target;
if (t) {
    NSLog(@"Not nil");
}else{
    NSLog(@"nil");
}

Hope it helps.

answered Mar 04 '15 at 11:00

sabadow

5,095
3
34
51

How to check if an object is nil in Objective-C?

4 Answers4