How to get the arity of the method?

Question

In Javascript, for example, you can get arity (the number of arguments the function should take) just func.length . How can I get this information for a method in Objective-C?

Answer 1

NSMethodSignature is terrific for all kinds of reflection information.

 SEL selector = @selector(foo:); NSMethodSignature *sig = [someObj methodSignatureForSelector:selector] int argCount = [sig numberOfArguments]; 

Answer 2

If the receiving object does not send -methodSignatureForSelector: to, you can use it NSStringFromSelector() and count the number of occurrences of the colon character.

Answer 3

From Objective-C Link to the working environment

method_getNumberOfArguments

Returns the number of arguments accepted by the Method.

unsigned method_getNumberOfArguments (method method) Parameter method Pointer to the data structure of the method. Go through the method in question. The return value is an integer containing the number of arguments accepted by this method.