Swift - 类型“*”不符合协议“*”

Question

I got this error message when trying to create a Message class.

'Message' does not conform to protocol 'JSQMessageData'

JSQMessageData got from https://github.com/jessesquires/JSQMessagesViewController

My code

import Foundation

class Message : NSObject, JSQMessageData {

    var senderId_ : String!
    var senderDisplayName_ : String!
    var date_ : NSDate
    var isMediaMessage_ : Bool
    var hash_ : Int = 0
    var text_ : String

    init(senderId: String, senderDisplayName: String?, isMediaMessage: Bool, hash: Int, text: String) {
        self.senderId_ = senderId
        self.senderDisplayName_ = senderDisplayName
        self.date_ = NSDate()
        self.isMediaMessage_ = isMediaMessage
        self.hash_ = hash
        self.text_ = text
    }

    func senderId() -> String! {
        return senderId_;
    }

    func senderDisplayName() -> String! {
        return senderDisplayName_;
    }

    func date() -> NSDate! {
        return date_;
    }

    func isMediaMessage() -> Bool! {
        return isMediaMessage_;
    }

    func hash() -> Int? {
        return hash_;
    }

    func text() -> String! {
        return text_;
    }
}

JSQMessageData.h

#import <Foundation/Foundation.h>
#import "JSQMessageMediaData.h"

@protocol JSQMessageData <NSObject>

@required

- (NSString *)senderId;
- (NSString *)senderDisplayName;
- (NSDate *)date;
- (BOOL)isMediaMessage;
- (NSUInteger)hash;

@optional

- (NSString *)text;
- (id<JSQMessageMediaData>)media;

@end

How to fix this protocol issue?

Answer 1

There are two problems:

1. hash is defined as a method that returns an NSUInteger in the protocol. Also, NSUInteger can't be nil in Objective-C, so you can't return an optional. You need to change its implementation in the Message class to return an UInt

    func hash() -> UInt { return UInt(hash_); }

or simply return hash_ and change hash_ from Int to UInt itself.

2. BOOL can't be nil in Objective-C, so to conform to the protocol you need to change isMediaMessage() to return a non optional Bool by removing the ! :

    func isMediaMessage() -> Bool { return isMediaMessage_; }

Answer 2

问题可能是“散列”，即协议中的 unsigned int 和实现中的 int。