开发中可能用到的Runtime：在Category中添加属性， 交换方法的实现，归档接档（获取所用的变量， 属性， 方法名， 协议名），动态添加方法

1：添加属性

objc_setAssociatedObject(self, _cmd, girlFriend, OBJC_ASSOCIATION_RETAIN);objc_getAssociatedObject(self, @selector(setGirlFriend:));

2：方法交换

+ (void)MethodSwapWithSEL:(SEL)sel1 otherSEL:(SEL)sel2 {    Method fromMethod = class_getInstanceMethod([self class], sel1);    Method toMethod = class_getInstanceMethod([self class], sel2);    method_exchangeImplementations(fromMethod, toMethod);}

3：获取所有的变量，属性，方法， 协议名

/// 变量    unsigned int count = 0;    Ivar *ivarList = class_copyIvarList([People class], &count);    for (int i = 0; i < count; i++) {        // 变量的名        NSString *ivarName = [NSString stringWithUTF8String:ivar_getName(ivarList[i])];        // 变量的类型        NSString *ivarType = [NSString stringWithUTF8String:ivar_getTypeEncoding(ivarList[i])];    }

unsigned int count = 0;    /// 属性    objc_property_t *propertyList = class_copyPropertyList([People class], &count);    /// 方法    Method *methodList = class_copyMethodList([People class], &count);    /// 协议    class_copyProtocolList([People class], &count);

4 动态添加方法

+ (BOOL)resolveClassMethod:(SEL)sel {    }+ (BOOL)resolveInstanceMethod:(SEL)sel {    }

 重定向

- (id)forwardingTargetForSelector:(SEL)aSelector {    }

 转发

- (NSMethodSignature *)methodSignatureForSelector:(SEL)aSelector {    }- (void)forwardInvocation:(NSInvocation *)anInvocation {    }