xcode Swift 4“此类不符合键值编码”
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Swift 4 "This class is not key value coding compliant"
提问by user1537360
I have a Swift library which is heavily reliant on obj.valueForKey()from NSObject.
我有一个雨燕库，是严重依赖obj.valueForKey()从NSObject。
After migrating to Swift 4 I've found that these calls always crash with the error "this class is not key value coding-compliant for the key..." unless the property I'm looking for is declared with @objc.
迁移到 Swift 4 后，我发现这些调用总是会因错误“此类不是键值编码兼容的键...”而崩溃，除非我要查找的属性是用@objc.
Is it now mandatory to declare properties with @objcfor them to be found with this method? Is there an alternative?
现在是否必须声明属性@objc才能使用此方法找到它们？有替代方案吗？
回答by nathan
When you performed the migration Xcode asked about @objcinference and you probably selected the new type instead of Swift3.
当您执行迁移时 Xcode 询问@objc推理，您可能选择了新类型而不是 Swift3。
Possible solutions:
可能的解决方案：
Use @objc
用 @objc
Use @objcon each method, as needed instead of the whole class.
@objc根据需要在每个方法上使用，而不是在整个类上使用。
Use @objcMembers
用 @objcMembers
You could just use @objcMemberson the class.
你可以@objcMembers在课堂上使用。
Applying @objcMembers attribute to a class implicitly adds the @objc attribute to all of its Objective-C compatible members.
Writing Swift Classes and Protocols with Objective-C Behavior
将@objcMembers 属性应用到一个类中会隐式地将@objc 属性添加到它的所有Objective-C 兼容成员中。
Keep in mind: because applying the @objc attribute can increase the compiled size of an app and adversely affect performance, only apply the @objcMembers attribute on declarations when each member needs to have the @objc attribute applied.
请记住：因为应用@objc 属性会增加应用程序的编译大小并对性能产生不利影响，所以只有在每个成员需要应用@objc 属性时才在声明上应用@objcMembers 属性。
Switch inference to the old behavior
将推理切换到旧行为
You can also change the project's behavior under:
Build Settings> Swift 3 @objc Inference> On/Off
您还可以在以下位置更改项目的行为：
Build Settings> Swift 3 @objc Inference> On/Off
Related questions:
相关问题：
