implicit declaration of function 'objc_lookUpClass'

Question

I am getting this warning for the line code:

Class myClass = objc_lookUpClass([_className UTF8String]);

I am adding

#import <Foundation/NSObjCRuntime.h>
#import <objc/objc.h>

And it still don't resolve the problem

Another warning i get on this line is: "Initialization makes pointer from integer without a cast"

Answer 1

If you check the doc, you'll see that objc_lookUpClass returns an id , not a Class . To suppress the warning you either need to make myClass an id , or cast the return value to a Class :

Class myClass = (Class)objc_lookUpClass([_className UTF8String]);

BTW, there is NSClassFromString if you have an NSString.

Class myClass = NSClassFromString(_className);

Answer 2

您必须导入此标头：

#import <objc/runtime.h>