在非ARC项目中使用ARC库 [英] Using ARC library in non-ARC project
问题描述
我的项目中未使用ARC技术.我正在尝试向其中添加 SBJson 库.我为所有带有SBJson前缀的文件设置了-fobjc-arc标志，但是在编译过程中，ARC语义问题(指向没有明确所有权的非const类型'id'的指针)出现在一个与SBJSon不相关的类头中.为什么不起作用?
ARC technology isn't being used in my project. I'm trying to add SBJson library to it. I set -fobjc-arc flag for all files which have SBJson prefix, but during compilation process ARC semantic issue (Pointer to non-const type 'id' with no explicit ownership) appears in one class header, which is not related to SBJSon. Why doesn't it work?
有错误的行:
id *_controls;
由于项目的商业许可，我无法向您显示我的代码，感谢您的理解.
I cannot show you my code because of commercial license of project, I appreciate your understanding.
当我使用该库的旧版本(不带ARC)时，项目编译正常进行.
Project compilation goes normally when I use older version of this library (without ARC).
推荐答案
问题是您正在通过包含将ARC违反结构混合到ARC文件中.您不能将-fno-objc-arc应用于单个头文件，因为那没有意义.
The issue is that you are mixing an ARC violating construct into ARC'd files through inclusion. You can't apply -fno-objc-arc to a single header file because that doesn't make sense.
由于该文件位于头文件中，因此您将需要使用#if编译指示根据正在编译ARC还是非ARC .m文件在行为之间进行切换.
Since it is in a header file, you will either need to use an #if pragma to switch between behaviors depending on whether an ARC or non-ARC .m file is being compiled.
但是，更好的解决方案是完全消除ARC和非ARC的问题.有了该声明，它几乎必须是一个实例变量(尽管它可以在结构中).
A better solution, however, is to eliminate the issue entirely for both ARC and non-ARC. Given that declaration, it pretty much has to be an instance variable (though it could be in a struct).
如果它是一个ivar，则完全摆脱声明.如果不需要在公共API中公开它，则可以通过@property公开它，也可以将其移动到.m文件中.给定类型后，它实际上应该是带有公共API的私有实现细节，这使得访问内容的指针魔术性降低了.
If it is an ivar, get rid of the declaration entirely. Either expose it through @property or move it to the .m file if it does not need to be exposed in your public API. Given the type, it really should be a private implementation detail with public API that makes accessing the contents a bit less pointer-magic.
通常不建议使用C语言数组(指针数组)存储Objective-C类型.如果_controls确实需要作为可公开访问的东西公开(对项目中的其他类公开)，则重构代码以使用集合类(即，通常使用内部仅供使用的UIView上的subviews.
In general, using C language arrays -- arrays of pointers -- to store Objective-C types is highly discouraged. If _controls does need to be exposed as a publicly accessible thing (public to the other classes in your project), then refactor your code to use a collection class (i.e. typically an exposed NSArray* getter with an internal-only NSMutableArray* backing store -- like subviews on UIView, for example).
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