自动引用计数:指向非 const 类型“NSError *"的指

Automatic Reference Counting: Pointer to non-const type #39;NSError *#39; with no explicit ownership(自动引用计数:指向非 const 类型“NSError *的指针，没有明确的所有权)

问题描述

在更新我的一些代码以与 iOS 5 SDK 兼容时，我尝试通过在 Xcode 中使用转换为 Objective-C ARC"来重构我的代码并收到错误.错误发生在我的 .h 文件中的实例变量上.

In updating some of my code to be in compatible with the iOS 5 SDK, I attempted to refactor my code by using "Convert to Objective-C ARC" in Xcode and received an error. The error occurs on an instance variable in my .h file.

NSError **_error;

错误提示指向非 const 类型 'NSError *' 的指针没有明确的所有权."我该如何解决这个问题?

The error says "Pointer to non-const type 'NSError *' with no explicit ownership." How might I fix this?

推荐答案

当将 NSError 对象存储在实例变量中时，您必须将其声明为简单指针:

When storing NSError objects in an instance variable you have to declare it as a simple pointer:

@interface Foo : NSObject
{
    NSError *_errror;
}

NSError ** 仅用于将 NSError 对象从方法间接返回给调用者.将其存储在实例变量中(可能)是错误的.

NSError ** is only used to indirectly return NSError objects from a method to the caller. It is (probably) an error to store it in an instance variable.

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