Returns the class definition of a specified class.
- iOS 2.0+
- macOS 10.0+
- tvOS 9.0+
- watchOS 1.0+
The name of the class to look up.
The Class object for the named class, or
nil if the class is not registered with the Objective-C runtime.
objc_get is different from
objc_look in that if the class is not registered,
objc_get calls the class handler callback and then checks a second time to see whether the class is registered.
objc_look does not call the class handler callback.
Earlier implementations of this function (prior to OS X v10.0) terminate the program if the class does not exist.