相关疑难解决方法(0)

我正在尝试将我的项目转换为Swift 3并继续收到此错误.我已经解决了所有其他错误,但这个错误.我看到其他一些人遇到了问题,但我是JSON的新手,所以我不理解它们.任何帮助将不胜感激.

这是我的代码:

class func fetchPriceForSymbol(_ symbol: String, completion:@escaping (_ stock: StockPrice) -> ()) {

    DispatchQueue.global(priority: DispatchQueue.GlobalQueuePriority.default).async {

        let url = URL(string: "http://finance.yahoo.com/webservice/v1/symbols/\(symbol)/quote?format=json")
        let data = try? Data(contentsOf: url!)

        do {
            //let object = try JSONSerialization.jsonObject(with: data!, options: .allowFragments)
            let object = try! JSONSerialization.jsonObject(with: data!)
            if let dictionary = object as? [String: AnyObject] {
                let title = object["list"] as! NSDictionary
                let title2 = title["resources"] as AnyObject!
                let title3 = title2[0] as AnyObject!
                let title4 = title3["resource"] as AnyObject!
                let fields …