'SessionDelegate'没有名为'xxx'的成员 [英] 'SessionDelegate' does not have a member named 'xxx'

问题描述

我之前曾询问过如何使用可选方法创建协议的问题。几乎使用Objective-c的反应。请参阅此处。

I previously asked a question on how to create a protocol with optional methods. The response was, pretty much, use Objective-c. See it here.

我做了，一切正常，因为我正在使用

I did, and everything worked fine, because I was using

var delegate: SessionDelegate?;

也就是说，delegate是一个可选的SessionDelegate。为了从该委托中调用方法，我可以简单地写：

That is, "delegate" is an optional SessionDelegate. In order to call methods from that delegate I could simply write:

self.delegate?.willOpenSession?(self);

哪个没问题。但是，然后我，为什么让代表可选？所以我改变了它：

Which was fine. But then I though, why make the delegate optional? So I changed it:

var delegate: SessionDelegate;

显然，电话也会改变：

self.delegate.willOpenSession?(self);

问题是，最后一行（以及任何其他类型）说：'SessionDelegate'确实如此没有名为'willOpenSession'的成员。为什么这不起作用？

The problem is, this last line (and any other of the kind) says: 'SessionDelegate' does not have a member named 'willOpenSession'. Why doesn't this work?

这是我的代码：

SessionDelegate.h

SessionDelegate.h

@class Session;

@protocol SessionDelegate <NSObject>

@optional
- (BOOL)willOpenSession:(Session*)session;
- (void)didOpenSession:(Session*)session;
- (void)didFailOpenningSession:(Session*)session withError:(NSError*)error;

- (BOOL)willCloseSession:(Session*)session destroyingToken:(BOOL)destroyingToken;
- (void)didCloseSession:(Session*)session destroyingToken:(BOOL)destroyingToken;

@end

xxx-Bridging-Header.h

xxx-Bridging-Header.h

#import <Foundation/Foundation.h>
#import <FacebookSDK/FacebookSDK.h>
#import "SessionDelegate.h"

Session.swift

Session.swift

import Foundation

protocol Session {

    var delegate: SessionDelegate { get set };

    var isOpen: Bool { get };
    var isCached: Bool { get };

    func open();
    func close();
    func destroy();
}

FacebookSession.swift

FacebookSession.swift

import Foundation

class FacebookSession : Session {

    var delegate: SessionDelegate;

    var isOpen: Bool {
    get {
        return FBSession.activeSession().isOpen;
    }
    }

    // TODO
    var isCached: Bool {
    get {
        return false;
    }
    }

    init(delegate: SessionDelegate) {
        self.delegate = delegate;
    }

    func open() {

        if self.isOpen {
            return;
        }

        // Trigger the "will" event
        self.delegate.willOpenSession?(self);

        // Handle session state changes
        var completionHandler: FBSessionStateHandler = {

            session, status, error in

            if error {

                // Login failed for some reason, so we notify the delegate.
                // TODO we should turn this NSError message into something more generic (that is, not facebook specific)
                self.delegate.didFailOpenningSession?(self, withError: error);
            }

            else if status.value == FBSessionStateClosedLoginFailed.value {

                // Login failed with no error. I'm not sure this ever happens
                self.delegate.didFailOpenningSession?(self, withError: error);
            }

            else if status.value == FBSessionStateOpen.value || status.value == FBSessionStateOpenTokenExtended.value {

                // Session is now open, we should notify the delegate
                self.delegate.didOpenSession?(self);
            }

            else {

                // There's no error but the session didn't open either. I don't think this ever happens, but if it does, what should we do here?
                abort();
            }
        };

        // Open the session, prompting the user if necessary
        if FBSession.openActiveSessionWithReadPermissions([], allowLoginUI: true, completionHandler: completionHandler) {

            // If we end up here, the session token must exist, se we now have an open session
            self.delegate.d didOpenSession?(self);
        }
    }

    func close() {

    }

    func destroy() {

    }
}

祝你好运。

编辑：我还尝试了以下

self.delegate.willOpenSession?(self as Session);

和

self.delegate.willOpenSession(self as Session);

两者均无效。

编辑：之后所有，如果我使用它不起作用

After all, it doesn't work if I use

var delegate: SessionDelegate?;

编辑：之前的更改也会更改错误消息。现在我有可选的SessionDelegate（正如我在上一个编辑中所说）和以下行

The previous change also changes the error message. Now I have optional SessionDelegate (as I said in the previous edit) and the following line

self.delegate?.willOpenSession?(self)

说：找不到会员'willOpenSession'

Says: "Could not find member 'willOpenSession'"

推荐答案

您收到此错误是因为您将 Session 定义为协议，但Objective-C方法 SessionDelegate 协议中的定义需要 Session 类或子类。在Swift中，您可以在方法定义中将协议名称与类名互换使用，但在Objective-C中存在差异：

You're getting this error because you define Session as a protocol, but the Objective-C method definitions in the SessionDelegate protocol are expecting a Session class or subclass. In Swift you can use protocol names interchangeably with class names in method definitions, but in Objective-C there's a difference:

- (void)willOpenSession:(Session *)session;    // expects instance of Session class or subclass
- (void)willOpenSession:(id<Session>)session;  // expects object conforming to Session protocol

从您发布的代码中我无法告诉您为什么' ve声明 Session 作为协议 - 它是否为不同的类添加功能？它可能是一个超级类 FacebookSession （可能是其他会话）只是继承自？将 Session 更改为类（以及存根方法）可以解决问题。否则，您需要更改 SessionDelegate 方法以期望 id< Session> ，但对我来说，打破了编译器。

From the code you posted I can't tell why you've declared Session as a protocol -- does it add functionality to disparate classes? Could it instead be a superclass that FacebookSession (and presumably other sessions) simply inherits from? Changing Session to a class (and stubbing the methods) would solve the issue. Otherwise you'll need to change your SessionDelegate methods to expect an id<Session>, but for me that broke the compiler.

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