Swift：致命错误：在展开可选值时意外发现 nil

Posted 2023-03-11

【中文标题】Swift：致命错误：在展开可选值时意外发现 nil

【英文标题】：Swift : fatal error: unexpectedly found nil while unwrapping an Optional value

【发布时间】：2015-05-15 12:31:53

【问题描述】：

我正在尝试访问 REST Web 服务，但它给出了这个 - 致命错误：在展开 Optional 值时意外发现 nil。

下面是代码 - 所以我有这个 RESTParser 类 -

protocol RESTParserDelegate

    func getReceiveData(data:NSMutableData,sender:RESTParser)


class RESTParser: NSObject, NSURLConnectionDataDelegate 


var receiveData: NSMutableData!
var requestConnection: NSURLConnection!
var delegate: RESTParserDelegate?

func receiveData(resData:NSMutableData)
    receiveData = resData


func requestConnection(reqConn:NSURLConnection)
    requestConnection = reqConn


func httpRequest(myRequest:NSMutableURLRequest)
    self.requestConnection = NSURLConnection(request: myRequest, delegate: self)


// NSURLConnectionDataDelegate methods

func connection(connection: NSURLConnection, didReceiveData data: NSData)
    self.receiveData?.appendData(data)


func connectionDidFinishLoading(connection: NSURLConnection)
    self.delegate?.getReceiveData(receiveData, sender: self) // error @ this line
    self.delegate = nil
    self.receiveData = nil
    self.requestConnection = nil

func connection(connection: NSURLConnection, didFailWithError error: NSError)
    NSLog("Failed with error - %@ ",error.localizedDescription)


func parseData(data:NSMutableData)

Error is @ this line - self.delegate?.getReceiveData(receiveData, sender: self) in connectionDidFinishLoading 函数。

并从我的项目详细信息视图控制器中调用它 - 但是一旦调用 getReceiveData 方法，就会出现这个致命错误。

class ProjectDetails_tab: UIViewController, RESTParserDelegate

override func viewDidLoad() 
    super.viewDidLoad();
    //var projectData: NSDictionary = [String:String]()

    var url:String = "http://domianName.com"

    var nsURL = NSURL(string: url)
    var createrequest: NSMutableURLRequest = NSMutableURLRequest(URL: nsURL!)

    createrequest.HTTPMethod = "GET"

    var rest = RESTParser()
    rest.delegate=self
    rest.httpRequest(createrequest)



func getReceiveData(data:NSMutableData,sender:RESTParser)   
    

【问题讨论】：

在哪一行出现此错误...放置一些断点并检查...

Error is @ this line - self.delegate?.getReceiveData(receiveData, sender: self) in connectionDidFinishLoading 函数。

【参考方案1】：

不清楚代码的哪一行出现了致命错误。但是您可以重新检查您的委托对象，或者：

// NSURLConnectionDataDelegate methods
func connection(didReceiveResponse: NSURLConnection, didReceiveResponse response: NSURLResponse) 
    // Recieved a new request, clear out the data object
    self.receiveData = NSMutableData()


func connection(connection: NSURLConnection, didReceiveData data: NSData)
    self.receiveData?.appendData(data)


func connectionDidFinishLoading(connection: NSURLConnection!) 
    // Request complete, self.data should now hold the resulting info

【讨论】：

Error is @ this line - self.delegate?.getReceiveData(receiveData, sender: self) in connectionDidFinishLoading 函数。并且委托方法定义没有！，仍然尝试但 dinn 工作

这是因为 'receiveData' 对象为零。您必须在消息“connection(didReceiveResponse: NSURLConnection, didReceiveResponse response: NSURLResponse)”中初始化该对象在我编辑的答案中查看第一个函数