我的混合打破了KVO

Question

我正在尝试实现isa调配,因为我需要在某些对象的dealloc方法中执行某些操作.我压倒一切 - (班级)班级; 返回原始类的方法(如KVO所做).一切正常,直到我尝试将观察者添加到混合对象.它只是崩溃了.

1. 0x00000000(0x00000000)()
2. _NSKeyValueRetainedObservationInfoForObject()中的0x0091d22a
3. 0x0092ec88 in - [NSObject(NSKeyValueObserverRegistration)_addObserver:forProperty:options:context:]()
4. 0x0092d6fd in - [NSObject(NSKeyValueObserverRegistration)addObserver:forKeyPath:options:context:]()

这是实施调酒

- (void)swizzleClass
{
    NSString *proxyClassName = [NSString stringWithFormat:@"MDSwizzled_%@", NSStringFromClass(self->isa)];
    Class proxyClass = NSClassFromString(proxyClassName);

    if (!proxyClass)
        proxyClass = [self createProxyClassWithName:proxyClassName];

    object_setClass(self, proxyClass);
}

- (Class)createProxyClassWithName:(NSString *)proxyClassName
{
    const char *c_proxyClassName = [proxyClassName cStringUsingEncoding:NSUTF8StringEncoding];
    Class proxyClass = objc_allocateClassPair(self->isa, c_proxyClassName, 0);

    Class dummyClass = [MDDummy class];
    class_addMethodFromClass(proxyClass, dummyClass, @selector(dealloc));
    class_addMethodFromClass(proxyClass, dummyClass, @selector(class));

    objc_registerClassPair(proxyClass);
    return proxyClass;
}

MDDummy它只是一种令人信服的类保持方法(这与添加原始函数没有区别).

@implementation MDDummy
- (void)dealloc
{

    //Special thinngs

    [super dealloc];
}

- (Class)class
{
    return //original class;
}
@end

编辑:

这是class_addMethodFromClass函数的实现:

void class_addMethodFromClass(Class class, Class sourceClass, SEL selector)
{
    Method method = class_getInstanceMethod(sourceClass, selector);
    IMP methodImplementation = method_getImplementation(method);
    const char *types = method_getTypeEncoding(method);
    class_addMethod(class, selector, methodImplementation, types);
}

Answer 1

您应该查看 Mike Ash 如何处理此问题：https://github.com/mikeash/MAZeroingWeakRef

摘要：以不同的方式处理 KVO 混合子类的混合——您必须修补 KVO 子类中的 KVO 方法...