其中是定义生成KeyValueObservingPublisher的“publisher(for:)”方法的标头?

它不在文档中,跳转到标题时在Xcode中不可见。然而,我发现它藏在一个 .swiftinterface Xcode中的文件:

@available(OSX 10.15, iOS 13.0, tvOS 13.0, watchOS 6.0, *)
extension _KeyValueCodingAndObservingPublishing where Self : ObjectiveC.NSObject {
    public func publisher<Value>(for keyPath: Swift.KeyPath<Self, Value>, options: Foundation.NSKeyValueObservingOptions = [.initial, .new]) -> ObjectiveC.NSObject.KeyValueObservingPublisher<Self, Value>
}

我认为这里的问题是这个方法是在一个协议的扩展中声明的 _KeyValueCodingAndObservingPublishing

编辑 https://github.com/apple/swift/blob/master/stdlib/public/Darwin/Foundation/Publishers%2BKeyValueObserving.swift .