我做了一个这样的类别:
@interface NSObject (defaultSelector)
+(NSString *) defaultSelector;
-(NSString *)defaultSelector;
@end
然后,我这样使用它:
-(void)prefetchShortcutWithTable: (Class) someNSManagedObjectClass forInputArray: (NSArray *) inputArray withDictCache: (NSMutableDictionary *) dictToSave
{
    NSString * attribute = [someNSManagedObjectClass defaultSelector];
    [self prefetchShortcutWithTable:NSStringFromClass(someNSManagedObjectClass) forAttribute:attribute forInputArray:inputArray withDictCache:dictToSave];
}
整个事情都有效。但是,编译器如何知道 someNSManagedObjectClass 将是 NSObject 的子类?
实际上,如何重写函数以便     -(void)prefetchShortcutWithTable: (Class) someNSManagedObjectClass forInputArray: (NSArray *) inputArray withDictCache: (NSMutableDictionary *) dictToSave只接受 NSManagedObject 的子类?