ios - Swift 3 中的 JSON 解析和可选项

Question

所以我最近更新到 Swift 3/XCode 8 并且我的一些代码乱七八糟。我读过一些语法更改，但我似乎无法正确理解这一点。我向 Twitter 发出请求并取回 JSON:

func forLoadStats(completion: (AnyObject?, NSError?) -> Void)
{
    var clientError: NSError?
    let idString = api.getUserID()
    let client = TWTRAPIClient()
    let request = client.urlRequest(withMethod: "GET", url: "https://api.twitter.com/1.1/users/show.json", parameters: ["user_id" : 27446437], error: &clientError)
    client.sendTwitterRequest(request)
   { (response, data, connectionError) in

    if (connectionError == nil)
    {
    do {
        if let json: Any = try? JSONSerialization.jsonObject(with: data!, options: .allowFragments) as? [AnyObject]
            {
            if let json = json, let immage = json?["profile_image_url_https"] as? String
                {
                //Make ProfilePic edges round
                self.profPic.layer.cornerRadius = 42
                self.profPic.clipsToBounds = true

                //let immage = image["profile_image_url_https"] as String
                let _vImageUrl = immage.replacingOccurrences(of: "_normal", with: "")
                let urlProfilePic = NSURL(string: _vImageUrl)
                let  urlPP = NSData(contentsOf: urlProfilePic! as URL)
                self.profPic.image = UIImage(data: urlPP! as Data)

                let ScrName = json["screen_name"] as! String
                self.scrNameLabel.text = "@\(ScrName)"

                //Populate Followers Label.text
                let flwrVar = json["followers_count"] as! Int
                self.followerLbl.text = "\(flwrVar)"

                //Populate Following Label.text
                let flwngVar = json["friends_count"] as! Int
                self.followingLbl.text = "\(flwngVar)"

                //Populate Bio
                let bio = json["description"] as! String
                self.bioLabel.text = "\(bio)"

                //created at date
                let accountAge = json["created_at"] as! String

                self.createdLbl.text = "\(accountAge)"

                let tweetCount = json["statuses_count"] as! Int
                self.tweetCount.text = "\(tweetCount)"

                let likes = json["favourites_count"] as! Int
                self.likesCount.text = "\(likes)"

                let lists = json["listed_count"] as! Int
                self.listedCount.text = "\(lists)"
                }
            }
        }
        catch let error
        {
            print(error)
        }
    }
}
}

我在第二个“If let”语句中收到错误消息:“条件绑定(bind)的初始化程序必须具有可选类型，而不是‘Any。谁能解释这是为什么？

Answer 1

你的 JSON 显然是一个字典，Swift 3 中的 JSON 字典是 [String:Any]

错误是由愚蠢的 Any 注释(应该是 Any? 但实际上是无意义的)引起的，因为它混淆了编译器。

如果您使用 do block ，try 不带问号但使用可选绑定(bind):

...
if let json = try JSONSerialization.jsonObject(with: data!, options: .allowFragments) as? [String:Any] {
   if let immage = json["profile_image_url_https"] as? String { ...