method_exchangeImplementations

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最新推荐文章于 2025-06-28 15:05:56 发布

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分类专栏： iOS-runtime iOS-Runtime 文章标签： ios runtime class_getInstanceMet method_exchangeImple

本文链接：https://blog.youkuaiyun.com/lvdezhou/article/details/49585439

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本文展示了如何使用Objective-C中的`method_exchangeImplementations`方法动态交换两个方法的实现，通过实例代码演示了方法调用前后实现变化的过程。

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method_exchangeImplementations运行时动态改变两个方法的实现

/** 
 * Exchanges the implementations of two methods.
 * 
 * @param m1 Method to exchange with second method.
 * @param m2 Method to exchange with first method.
 * 
 * @note This is an atomic version of the following:
 *  \code 
 *  IMP imp1 = method_getImplementation(m1);
 *  IMP imp2 = method_getImplementation(m2);
 *  method_setImplementation(m1, imp2);
 *  method_setImplementation(m2, imp1);
 *  \endcode
 */
OBJC_EXPORT void method_exchangeImplementations(Method m1, Method m2) 
     __OSX_AVAILABLE_STARTING(__MAC_10_5, __IPHONE_2_0);

代码：

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
    
    Method m1 = class_getInstanceMethod([self class], @selector(testExchange1));
    
    Method m2 = class_getInstanceMethod([self class], @selector(testExchange2));
    
    [self testExchange1];
    
    [self testExchange2];
    
    method_exchangeImplementations(m1, m2);
    
    [self testExchange1];
    
    [self testExchange2];
    
}

- (void) testExchange1 {
    NSLog(@"%s", __func__);
}
- (void) testExchange2 {
    NSLog(@"%s", __func__);
}

输出：

2015-11-02 13:38:40.264 02-runtime[2485:68367] -[ViewController testExchange1]
2015-11-02 13:38:40.266 02-runtime[2485:68367] -[ViewController testExchange2]
2015-11-02 13:38:40.281 02-runtime[2485:68367] -[ViewController testExchange2]
2015-11-02 13:38:40.281 02-runtime[2485:68367] -[ViewController testExchange1]

通过代码相信很容易理解吧