How to access instance method using "self" in singleton class?

Question

I am accessing instance method in a class method by using self in singleton class it shows error, but if I try to access instance method with parameter using self then its perfectly working, so basically i want to know the reason, why i am not able to access this.

like

-(void)someMethodA:(NSString *)paramA withParamB:(NSString *)paramB;

-(void)someMethodB;

if i try to use "someMethodA" with self then it works perfectly fine, but accessing "someMethodB" using self it gives error

+(void)someMethod

{

   [self someMethodA:@"string" withParamB:@"string"]; works fine

   [self someMethodB]; gives error

}

"No known class method for selector" Basically I am using methods inside a class method i.e method starting with "+" — Prashant Goyal
– Prashant Goyal, Commented Apr 1, 2016 at 6:43
You can't use self within a class method to refer to an instance method - self doesn't refer to an instance in this case. Are you sure that someMethodA isn't defined as a class method also (+)? — Paulw11
– Paulw11, Commented Apr 1, 2016 at 6:50
I doubt that your message to someMethodA: is working fine being it an instance method. Check This thread for further understanding. — Gandalf
– Gandalf, Commented Apr 1, 2016 at 6:56
As I said above and as the answers on the question that @Gandalf linked to explains, instance methods need to operate on an instance. A class is not an instance. You can call the instance method on your singleton instance, but not on self directly. — Paulw11
– Paulw11, Commented Apr 1, 2016 at 7:02

gunjot singh · Accepted Answer · 2016-04-01 06:54:34Z

0

Instance methods(methods that start with '-' ) can only be accessed by other instance methods, while class methods(methods that start with '+') can be accessed from anywhere by using [CLASS_NAME methodName]

So if you need to access someMethodB from your class method, then simply update it to class method as below:

+(void)someMethodB;

answered Apr 1, 2016 at 6:54

gunjot singh

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