Swift 3中類型轉換期間發生錯誤

Question

我正在學習Swift動畫。 它的材料是用Swift 2編寫的，所以我不得不將其原始代碼轉換為Swift3。我從中學到了很多，但是現在我遇到了一個大問題。 Xcode成功構建了此代碼，但產生了運行時錯誤消息。 （我附加了圖像文件。）

我完全無法解決這個問題，因為我覺得我經驗不足。 我怎樣才能解決這個問題？ 救命。

func setQuote() {

    //fadeOut


    //getting data from API
    let dataService = DataService()
    dataService.getQuoteData {(quote, author) -> Void in

        UIView.animate(withDuration: 0.5, animations: {

            //fadeIn and backgroundColor


            //quote
            self.quoteLabel.text = quote


            //author - optional binding

            //if no author


            }, completion:nil)


    }
}


class DataService {

    func getQuoteData(_ completion: @escaping (_ quote: String, _ author: String?) -> ()) {

        let url = URL(string: "http://api.forismatic.com/api/1.0/?method=getQuote&lang=en&format=json")!

        URLSession.shared.dataTask(with: url, completionHandler: { ( data: Data?, response: URLResponse?, error: NSError?) -> Void in

            do {
                let jsonDictionary = try JSONSerialization.jsonObject(with: data!, options: JSONSerialization.ReadingOptions.mutableContainers) as! NSDictionary

                let aQuote = jsonDictionary["quoteText"] as! String
                let aAuthor = jsonDictionary["quoteAuthor"] as! String

                DispatchQueue.main.async(execute: { () -> Void in
                    completion(aQuote, aAuthor)
                })

            } catch {
                print("invalid json query")
            }
        } as! (Data?, URLResponse?, Error?) -> Void).resume()
    }

}

Answer 1

您可以嘗試像這樣重寫它

    let task = URLSession.shared.dataTask(with: url) { (data, response, error) in
        do {
            let jsonDictionary = try JSONSerialization.jsonObject(with: data!, options: JSONSerialization.ReadingOptions.mutableContainers) as! NSDictionary

            let aQuote = jsonDictionary["quoteText"] as! String
            let aAuthor = jsonDictionary["quoteAuthor"] as! String

            DispatchQueue.main.async(execute: { () -> Void in
                completion(aQuote, aAuthor)
            })

        } catch {
            print("invalid json query")
        }
    }

    task.resume()

或簡單地將( data: Data?, response: URLResponse?, error: NSError?) -> Void更改為( data, response, error) -> Void並刪除as! ... as! ...