当 Swift 桥接头导入一个导入 Hopscotch-Swift.h 本身的文件时如何防止循环引用 [英] How to prevent circular reference when Swift bridging header imports a file that imports Hopscotch-Swift.h itself

问题描述

我正在将 Swift 集成到一个现有的大型 Objective C 项目中，并且遇到了我认为是循环引用的问题.

I am integrating Swift into a large existing Objective C project and have run into what I think is a circular reference.

有问题的类如下:

#import "Hopscotch-Swift.h"

@interface MyController : UIViewController<MyProtocol>
   ...
@end

Swift 协议

@objc protocol MyProtocol: NSObjectProtocol {
   ...
}

桥接标题

#import "MyController.h"

此代码无法编译，因为 Hopscotch-Swift.h 文件不会生成.

This code fails to compile because the Hopscotch-Swift.h file will not generate.

我认为这是由于循环引用错误，因为我可以将 Hopscotch-Swift.h 导入到不包含在 Hopscotch-Bridging-Header.h，它工作正常.

I think this is due to a circular reference error as I can import Hopscotch-Swift.h into objective c headers that are not included in Hopscotch-Bridging-Header.h and it works fine.

是否有解决此问题的方法，或者我应该向 Apple 提交雷达报告?

Is there a workaround for this issue or should I file a radar with Apple?

推荐答案

在您的情况下，前向声明应该有效.

Forward declaration should work, in your case.

在您的 .h 中:

@protocol MyProtocol;

@interface MyController : UIViewController<MyProtocol>

@end

在您的 .m 中:

#import "HopScotch-Swift.h"

来自 如何我添加了 -Swift.h 头文件中使用的前向类引用? 和 Swift 互操作性指南:

From How can I add forward class references used in the -Swift.h header? and the Swift interoperability guide:

如果您在 Swift 代码中使用自己的 Objective-C 类型，请确保在将 Swift 生成的头文件导入到要访问 Swift 的 Objective-C .m 文件之前，为这些类型导入 Objective-C 头文件代码来自.

If you use your own Objective-C types in your Swift code, make sure to import the Objective-C headers for those types prior to importing the Swift generated header into the Objective-C .m file you want to access the Swift code from.

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