Question

我要补充一些方法,以分类执行SOManagedObject议定书的NSManagedObject。我试图这样界定:

@interface NSManagedObject <SOManagedObject> (MyExtensionMethods)
    ...
@end

...but that doesn t seem to be valid. How do I define a category that adds methods to classes which implement a particular protocol?

Answer 1

在所有这些类别中界定这种类别不易被搁置。但你的实际问题似乎更为简单: 如何在<代码>NSManagedObject上添加一种类别方法,仅用于实施<代码>和lt的子类; 目标和效果; 这可减半。

你们想做的是,在<代码>上添加方法。 NSManagedObject,然后检查你重新工作的事例能够处理你希望从<发送的信息;SOManaged 目标和编号;。

Let us suppose that we are given:

/* SOManagedObject.h */
@protocol SOManagedObject
- (void)frobble_so;
- (void)bobble_so;
@end

Now let s add a category method to all NSManagedObject subclasses that implement SOManagedObject:

/* NSManagedObject+SOConvenience.h */
@interface NSManagedObject (SOConvience)
/* Frobbles and bobbles - no effect on non-<SOManagedObject>-conforming
 * instances. */
- (void)frobbleAndBobble_so;
@end

为了做到这一点,我们采用这样的方法:

/* NSManagedObject+SOConvenience.m */
@implementation NSManagedObject (SOConvenience)
- (void)frobbleAndBobble_so
{
    if (![self conformsToProtocol:@protocol(SOManagedObject)]) return;

    NSLog(@"%s: Thunderbirds are GO! Let s frobble and bobble!", __func__);
    [self frobble_so];
    [self bobble_so];
}
@end

You could optionally assert to ensure you are not sending the method to the wrong objects, or you could use respondsToSelector: instead of checking for protocol conformance. Whatever floats your boat, but this general tack should take you where you want to go.

Answer 2

我认为这是不可能的。此前曾回答过类似问题:

。

Answer 3

Edit:我错过了问题;我认为,如果没有目标C的运行时间,你可以做些什么。下面请见Dave s评论,说明我的答复为何不正确。

如果你放弃议定书和同类通知,你就能够这样做:

@interface NSManagedObject (MyExtensionMethods) <SOManagedObject>
    ...
@end

Answer 4

Adam Sharp 。

It involves 3 steps:

Defining the methods you want to add as @optional on a protocol.
Making the objects you want to extend conform to that protocol.
Copying those methods into those objects at runtime.

详细情况说明链接。

友情链接