```
- (void)AZ_addObserver:(NSObject *)observer forKeyPath:(NSString *)keyPath options:(NSKeyValueObservingOptions)options context:(nullable void *)context{
NSString * newClassName = [@"azhi" stringByAppendingString:NSStringFromClass([self class])];
Class newClass =? objc_allocateClassPair([self class], newClassName.UTF8String, 0);
class_addMethod(newClass, @selector(setName:), (IMP)setName, "v@:@");
objc_registerClassPair(newClass);
object_setClass(self, newClass);
objc_setAssociatedObject(self, @"hehe", observer, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
}
```
void setName(id self,SEL _cmd,NSString*name){
id observer = objc_getAssociatedObject(self, @"hehe");
objc_msgSend(observer, @selector(observeValueForKeyPath:ofObject:change:context:),@"name",self,@{@"new":name},nil);
id class = [self class];
object_setClass(self, [self superclass]);
objc_msgSend(self, @selector(setName:),name);
object_setClass(self, class);
}
```
