我正在将Swift 2项目转换为Swift3。现在,我使用Firebase来存储数据,并具有以下功能:

self.ref.child("languages").observeSingleEvent(of: .value, with: { (snapshot) in
            let languages = snapshot.value as! [String : AnyObject]
            var languageList = [Language]()
            for (key, value) in languages {
                let tempLanguage = Language()
                tempLanguage.objectId = key
                tempLanguage.code = value["code"] as! String
                tempLanguage.desc = value["fulldesc"] as! String
                languageList.append(tempLanguage)
            }
            handler(success: languageList, failure: nil)
        }) { (error) in
            handler(nil, error)
        }


在swift 2中还可以,但是现在在Swift 3中,我在行中收到一个错误。错误如下:


  无法将类型(AnyObject?)-> Void的值转换为预期的参数类型((Error)-> Void)?


我删除了该函数,并使用自动完成功能,再次编写了它,这是同样的问题。

最佳答案

只需将您的代码更改为:-

 FIRDatabase.database().reference().child("languages").observeSingleEvent(of: .value, with: { (snapshot) in

        let languages = snapshot.value as! [String : AnyObject]
        var languageList = [Language]()
        for (key, value) in languages {
            let tempLanguage = Language()
            tempLanguage.objectId = key
            tempLanguage.code = value["code"] as! String
            tempLanguage.desc = value["fulldesc"] as! String
            languageList.append(tempLanguage)
        }
        handler(success: languageList, failure: nil)

        }, withCancel: {(error) in

          handler(nil, error)

    })

10-05 20:26
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