In Objective-C, what is the equivalent of Java's “instanceof” keyword?
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22-08-2019 - |
Question
I would like to check whether an object (e.g. someObject
) is assignable (cast-able) to a variable of another type (e.g. SpecifiedType
). In Java, I can write:
someObject instanceof SpecifiedType
A related question is finding whether the runtime type of an object is equal to a another type. In Java, I can write:
someObject.getClass().equals(SpecifiedType.class)
How can this be done in Objective-C?
Solution
Try [myObject class]
for returning the class of an object.
You can make exact comparisons with:
if ([myObject class] == [MyClass class])
but not by using directly MyClass
identifier.
Similarily, you can find if the object is of a subclass of your class with:
if ([myObject isKindOfClass:[AnObject class]])
as suggested by Jon Skeet and zoul.
OTHER TIPS
From Wikipedia:
In Objective-C, for example, both the generic
Object
andNSObject
(in Cocoa/OpenStep) provide the methodisMemberOfClass:
which returnstrue
if the argument to the method is an instance of the specified class. The methodisKindOfClass:
analogously returns true if the argument inherits from the specified class.
isKindOfClass:
would be closest to instanceof
, by the sounds of it.
See the isKindOfClass: method in the NSObject documentation. (The usual word of warning for such question is that checking the object class is often a sign of doing something wrong.)