Working with Methods - method_invoke

1. method_invoke

Note: way to eliminate compiler warnning

        . ENABLE_STRICT_OBJC_MSGSEND = NO; 

        . int (*action)(id, SEL, int) = (int (*)(id, SEL, int)) objc_msgSend;

Description:   Calls the implementation of a specified method.

Declaration: id method_invoke(id receiver,Method m, ...) 

Example:

@interface KSModel4CheckMethod : NSObject

 + (void)classPrint;
 - (void)instancePrint;
 @end

 @implementation KSModel4CheckMethod

 #define PRINT_CMD NSLog(@"%@", NSStringFromSelector(_cmd))

 + (void)classPrint {
    PRINT_CMD;
}

- (void)instancePrint {
    PRINT_CMD;
}
@end

#import <Foundation/Foundation.h>
#import <objc/runtime.h>
#import <objc/message.h>
#import "KSModel4CheckMethod.h"

void test_0_getName_NSString();

int main(int argc, const char * argv[]) {
    @autoreleasepool {
        test_0_method_invoke();
    }
    return 0;
}

void test_0_method_invoke() {

    KSModel4CheckMethod *instance = [[KSModel4CheckMethod alloc] init];
    Class clazz = [KSModel4CheckMethod class];
    Method clazz_method = class_getClassMethod(clazz, @selector(classPrint));
    Method instance_method = class_getInstanceMethod(clazz, @selector(instancePrint));

//    Method clazz_method = class_getClassMethod(clazz, @selector(instancePrint));
//    Method instance_method = class_getInstanceMethod(clazz, @selector(classPrint));
//    method_invoke(clazz, nil);
//    method_invoke(instance, nil);

    method_invoke(clazz, clazz_method);
    method_invoke(clazz, instance_method);
    method_invoke(instance, clazz_method);
    method_invoke(instance, instance_method);
}

 

Result:

1. method should be fetched from class

    class_getClassMethod(instance, @selector(instancePrint)) or 

    class_getInstanceMethod(instace, @selector(classPrint))  Return nil

2. 2rd parameter with nil would lead to crash

    method_invoke(clazz, nil);

    method_invoke(instance, nil);

3. 1rd parameter with instance or class  would produce same output

    method_invoke(clazz, clazz_method);

    method_invoke(clazz, instance_method);

    method_invoke(instance, clazz_method);

    method_invoke(instance, instance_method);

 

Deepening:

1.How do methods stored in logic and in physic