Xcode 7 错误代码“无法转换值类型([AnyObject]

Question

这是我的代码副本，其中出现错误，错误位于显示 query.findobjectsInBackgroundWithBlock 的行上。完整的错误消息是这样的:“无法将值类型 ([AnyObject]!, NSError!) -> Void 转换为预期的参数类型 'PFQueryArrayResultBlock?'

// Retrieve Messages
func retrieveMessages() {

    // Create a new PFQuery
    var query:PFQuery = PFQuery(className: "Message")

    // Call findobjectsinbackground
    query.findObjectsInBackgroundWithBlock {(objects:[AnyObject]!, error:NSError!) -> Void in

    // Clear the messagesArray

        self.messageArray = [String]()
        // Loops through the objects
    for messageObject in objects {

        // Retrieve the text column value of each PFObject
        let messageText:String? = (messageObject as! PFObject)["Text"] as? String
        // Assign it into our messagesArray
        if messageText != nil {
            self.messageArray.append(messageText!)
        }
    }
        // Reload the tableview
    self.messageTableView.reloadData()
    }
}

Answer 1

方法签名在 Swift 2.0 中通过 Parse SDK 1.10.0 得到了改进。将 [AnyObject]! 替换为 [PFObject]?。 [PFObject] 是可选的，因为 Swift 不知道它是否存在。

func retrieveMessages() {

var query:PFQuery = PFQuery(className: "Message")

query.findObjectsInBackgroundWithBlock { (objects: [PFObject]?, error: NSError?) -> Void in

    self.messageArray = [String]()

    for messageObject in objects {

        let messageText:String? = (messageObject as! PFObject)["Text"] as? String

        if messageText != nil {
            self.messageArray.append(messageText!)
        }
    }

    self.messageTableView.reloadData()
}
}