如何使用具有自动引用计数的委托 [英] how to use delegates with Automatic Reference Counting

问题描述

我跳过了ARC的潮流。在过去，我会将我的委托属性声明为：

I've jumped on the ARC bandwagon. In the past I would have my delegate properties declared like this:

@property(assign) id<MyProtocol> delegate;

所以我想我会在ARC下这样做：

So I thought I would do this under ARC:

@property(weak) id<MyProtocol> delegate;

不是这样。在.m中的@synthesize语句中，我有一个编译错误：

Not so. On the @synthesize statement in the .m I have a compile error:

*语义问题：__ weak属性的现有ivar'委托'代表'必须是__weak *

*Semantic Issue: Existing ivar 'delegate' for __weak property 'delegate' must be __weak*

我已经声明它虽然很弱！另外，我如何将实现协议的类传递给弱引用的属性。我是否必须将其包裹在其中一个奇怪的obj_unretained调用中？

I HAVE declared it as weak though! Also how do I pass a class implementing a protocol to a weakly referenced property. Do I have to wrap it in one of those weird obj_unretained calls?

对此的任何帮助都将非常感激。

Any help on this would be very much appreciated.

推荐答案

ivar表示实例变量，您尚未显示。我认为它看起来像这样：

"ivar" means "instance variable", which you have not shown. I'm betting it looks something like this:

@interface Foo : NSObject {
    id delegate;
}

@property (weak) id delegate;

错误的含义是它必须如下所示：

What the error is saying is that it must look like this:

@interface Foo : NSObject {
    __weak id delegate;
}

@property (weak) id delegate;

如果财产声称属弱，则该值最终存储的ivar必须较弱还有。

If the property claims to be weak, the ivar that the value ends up being stored in must be weak as well.

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