类型抛出函数的无效转换

Question

我正在尝试将我的代码转换为 Swift 2，但我在使用最后一个函数时遇到了问题。我在 task:

的声明中收到以下错误

Invalid conversion from throwing function of type ... to non throwing type.

    func performSearch(searchTerm: String){
    let session = NSURLSession.sharedSession()

    let task = session.dataTaskWithURL(urlForQuery(searchTerm)!, completionHandler: { (data: NSData?, response: NSURLResponse?, error: NSError?) -> Void in
        do {
        let result: NSDictionary = try NSJSONSerialization.JSONObjectWithData(data!, options:NSJSONReadingOptions.MutableContainers) as! NSDictionary
        }
        let results: AnyObject? = result.objectForKey("results")

        if let testVar: NSMutableArray = results as? NSMutableArray {
                // Uncomment this to print all feeds
                 //println(testVar)
                self.searchedPodcasts.removeAllObjects()
                self.searchedPodcasts.addObjectsFromArray(testVar as [AnyObject])
                NSNotificationCenter.defaultCenter().postNotificationName("SearchPerformed", object: self)
        }

        })

        task!.resume()     
}

我尝试了以下方法，但它也不起作用，这也意味着我出于某种原因无法调用 task.resume：

    func performSearch(searchTerm: String){
    let session = NSURLSession.sharedSession()
     do {   
    let task = session.dataTaskWithURL(urlForQuery(searchTerm)!, completionHandler: { (data: NSData?, response: NSURLResponse?, error: NSError?) -> Void in
        do {
        let result: NSDictionary = try NSJSONSerialization.JSONObjectWithData(data!, options:NSJSONReadingOptions.MutableContainers) as! NSDictionary
        }
        let results: AnyObject? = result.objectForKey("results")

        if let testVar: NSMutableArray = results as? NSMutableArray {
                // Uncomment this to print all feeds
                 //println(testVar)
                self.searchedPodcasts.removeAllObjects()
                self.searchedPodcasts.addObjectsFromArray(testVar as [AnyObject])
                NSNotificationCenter.defaultCenter().postNotificationName("SearchPerformed", object: self)
        }

        })
    } catch {
          print("error)
    }
        task!.resume()     
}

我该如何解决？

编辑：试过了，但仍然返回相同的错误。

     func test(searchTerm: String) {
    let session = NSURLSession.sharedSession()
    do {
        let task = try session.dataTaskWithURL(urlForQuery(searchTerm)!, completionHandler: { (data: NSData?, response: NSURLResponse?, error: NSError?) -> Void in
             let result: NSDictionary = try NSJSONSerialization.JSONObjectWithData(data!, options:NSJSONReadingOptions.MutableContainers) as! NSDictionary
        })
    } catch  {
            print("hello")
        }
    }

Answer 1

尝试在您的 do-try-catch 句子中添加一个 catch 块：

do {
    let result: NSDictionary = try NSJSONSerialization.JSONObjectWithData(data!, options:NSJSONReadingOptions.MutableContainers) as! NSDictionary
}
catch {
    print("error");
}

您还需要在外部声明 result 变量或在 do 块内移动更多代码。

有关异常处理的更多信息，请参阅 Swift 2 check out this guide。

Answer 2

Apple 在 Swift 2.

中用 ErrorType 替换了 NSError

因此，将您自己对 NSError 的显式使用替换为 ErrorType，并且您不需要其他答案中建议的额外 try catch 块，并且您可以用更少的代码来表达错误处理。

类型抛出函数的无效转换

Invalid conversion from throwing function of type

swift

swift2