iPhone how to check the type of an Object?

问题:

I want to check the type of an Object. How can I do that?

The scenario is I'm getting an object. If that object is of type A then do some operations. If it is of type B then do some operations. Currently the type of the object is C that is parent of A and B.

I have two classes AViewController andBViewController. The object I'm getting in UIViewController. Now how to check whether the object is AViewController or BViewController?

回答1:

if([some_object isKindOfClass:[A_Class_Name class]])
{
    // do somthing
}

回答2:

There are some methods on NSObject that allow you to check classes.

First there's -class which will return the Class of your object. This will return either AViewController or BViewController.

Then there's two methods, -isKindofClass: and isMemberOfClass:.

-isKindOfClass: will compare the receiver with the class passed in as the argument and return true or false based on whether or not the class is the same type or a subclass of the given class.

-isMemberOfClass: will compare the receiver with the class passed in as the argument and return true or false based on whether or not the class is strictly the same class as the given class.

回答3:

A more common pattern in Objective-C is to check if the object responds to the methods you are interested in. Example:

if ([object respondsToSelector:@selector(length)]) {
    // Do something
}

if ([object conformsToProtocol:@protocol(NSObject)]) {
    // Do something
}