我正在尝试执行以下操作：
>获得一个类’dealloc IMP
>向所述类注入一个自定义IMP,它基本上调用原始的dealloc IMP
>当所述类的实例被释放时,两个IMP都应该运行.
这是我的尝试：
@implementation ClassB
- (void)dealloc
{
NSLog(@"\n%@ | %@",self,NSStringFromSelector(_cmd));
}
@end
@implementation ClassC
- (void)swizzleMe:(id)target
{
SEL originalDeallocSelector = NSSelectorFromString(@"dealloc");
__block IMP callerDealloc = [target methodForSelector:originalDeallocSelector];
const char *deallocMethodTypeEncoding = method_getTypeEncoding(class_getInstanceMethod([target class],originalDeallocSelector));
IMP newCallerDealloc = imp_implementationWithBlock(^(id _caller) {
NSLog(@"\n new dealloc | calling block %p for %@",callerDealloc,_caller);
callerDealloc(_caller,originalDeallocSelector);
});
NSLog(@"\nswapping %p for %p",newCallerDealloc,callerDealloc);
class_replaceMethod([target class],originalDeallocSelector,deallocMethodTypeEncoding);
}
@end
像这样使用：
ClassB *b = [[ClassB alloc] init]; ClassC *c = [[ClassC alloc] init]; [c swizzleMe:b];
但结果是：
禁用僵尸对象：
2013-07-03 13:24:58.368 runtimeTest[38626:11303] swapping 0x96df020 for 0x2840 2013-07-03 13:24:58.369 runtimeTest[38626:11303] new dealloc | calling block 0x2840 for <ClassB: 0x93282f0> 2013-07-03 13:24:58.370 runtimeTest[38626:11303] <ClassB: 0x93282f0> | dealloc 2013-07-03 13:24:58.370 runtimeTest[38626:11303] new dealloc | calling block 0x2840 for <ClassB: 0x93282f0> 2013-07-03 13:24:58.371 runtimeTest[38626:11303] <ClassB: 0x93282f0> | dealloc runtimeTest(38626,0xac55f2c0) malloc: *** error for object 0x93282f0: pointer being freed was not allocated *** set a breakpoint in malloc_error_break to debug 2013-07-03 13:24:58.371 runtimeTest[38626:11303] new dealloc | calling block 0x2840 for <ClassB: 0x93282f0> 2013-07-03 13:24:58.372 runtimeTest[38626:11303] <ClassB: 0x93282f0> | dealloc
启用僵尸对象(第11行是图片中的EXC_BAD_ACCESS)
2013-07-03 13:34:37.466 runtimeTest[38723:11303] swapping 0x97df020 for 0x2840 2013-07-03 13:34:37.467 runtimeTest[38723:11303] new dealloc | calling block 0x2840 for <ClassB: 0x715a920> 2013-07-03 13:34:37.468 runtimeTest[38723:11303] <ClassB: 0x715a920> | dealloc
关于我做错了什么的任何想法？
解决方法
如果您真的想知道何时取消分配对象,则使用关联的对象.
具体而言,将对象与您要观察的对象相关联,使得被观察的对象具有唯一的强引用 – 唯一的保留引用 – 对象.然后,您可以覆盖dealloc并知道在调用它时,被观察的对象已经(或者即将被)释放.
不要乱解被解除分配的对象,尽管!!它已经调用了所有的dealloc方法(通过继承),因此内部状态将完全未定义.
请注意,如果您的目标是尝试清理系统框架中的某些内容,那么……不要.沿着这条道路走下去并不是不稳定和痛苦.
like I mentioned in the comments to nielsbot,I am NOT trying to know
when an object is deallocated.
准确了解注入的dealloc实现中的内容会很有帮助.从表面上看,我能想到的唯一原因是无法通过使用相关对象来检测解除分配,这正是因为你试图改变类的dealloc的行为,这对于做.
