runtime-class_addMethod\objc_msgSend\NSInvocation-优快云博客

本文链接：https://blog.youkuaiyun.com/james_1010/article/details/23767653

本文介绍如何使用Objective-C运行时API动态地为类添加方法，并通过两种方式调用这些方法：直接发送消息和使用NSInvocation。文章还提供了一个具体的例子来展示整个过程。

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#import <objc/runtime.h>

#import <objc/message.h>

  TestClass *instance = [[TestClass alloc]init];
    //给testclass添加一个fun
    class_addMethod([TestClass class],@selector(ocMethodA::), (IMP)cfunctionA,"@@:@@");
    
    
    
    if ([instance respondsToSelector:@selector(ocMethodA::)]) {
        
        NSLog(@"Yes, instance respondsToSelector:@selector(ocMethodA::)");
        NSString *myString = @"我是一个OC的method，C函数实现";
        NSString *myString2 = @"-----我是第二个参数";
        
        
        //方法1
        objc_msgSend(instance, @selector(ocMethodA::),myString,myString2);
        
        
        //方法2
        SEL mySelector = @selector(ocMethodA::);
        NSMethodSignature * sig = [[TestClass class]  instanceMethodSignatureForSelector: mySelector];
        NSInvocation * myInvocation = [NSInvocation invocationWithMethodSignature: sig];
        [myInvocation setTarget: instance];//0
        [myInvocation setSelector: mySelector];//1
        [myInvocation setArgument: &myString atIndex: 2];
        [myInvocation setArgument: &myString2 atIndex: 3];
        NSString* result = nil;
        [myInvocation retainArguments];
        [myInvocation invoke];
        [myInvocation getReturnValue: &result];
        NSLog(@"The NSInvocation invoke string is: %@", result);
        
    }
    else
    {
        
        NSLog(@"Sorry");
        
    }

NSString* cfunctionA(id self, SEL _cmd, NSString *str, NSString *str1) {
    
    NSLog(@"%@%@", str,str1);
    
    return @"结果返回";//随便返回个值
    
}