Question

我正在尝试将我的代码转换为Swift 2，并且我遇到了最后一个函数的问题。我在task的声明中得到了以下错误：

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()     
}

我尝试过以下操作，但它也不起作用，这也意味着我无法出于某种原因调用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()     
}

我该怎么做才能解决它？

编辑：试过这个，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do-try-catch句中添加一个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块中移动更多代码。

有关Swift 2 check out this guide中的异常处理的更多信息。

Answer 2

Apple在Swift 2中用ErrorType替换了NSError。

因此，用ErrorType替换你自己对NSError的显式使用，你不需要在另一个答案中建议的额外的try catch块，你可以用更少的代码表达你的错误处理。

投掷函数类型的转换无效

2 个答案: