Question

我遇到了新问题＆＃34;抛出＆＃34; - ＆＃34;尝试＆＃34;参数。

我收到错误添加这些单词，所以我添加了＆＃34; throws＆＃34;在IBAction函数结束时。

@IBAction func loginButtonPressed(sender: AnyObject)throws {//code here}

在里面我找了一些不相干的东西然后这个：

let jsonData:NSDictionary = try NSJSONSerialization.JSONObjectWithData(urlData!, options:NSJSONReadingOptions.MutableContainers ) as! NSDictionary

之后没有错误，但是当我运行应用程序并单击按钮时，应用程序崩溃了代码

2015-06-15 10：43：11.374 BottLED [7283：1175818] - [BottLED.loginViewController loginButtonPressed：]：无法识别的选择器发送到实例0x7fee28da7d20 2015-06-15 10：43：11.381 BottLED [7283：1175818] *由于未捕获的异常终止应用程序＆＃39; NSInvalidArgumentException＆＃39;，原因：＆＃39; - [BottLED.loginViewController loginButtonPressed：]：无法识别的选择器发送到实例0x7fee28da7d20＆＃39; * 第一次抛出调用堆栈：（ 0 CoreFoundation 0x000000010d67c885 exceptionPreprocess + 165 1 libobjc.A.dylib 0x000000010cd0edf1 objc_exception_throw + 48 2 CoreFoundation 0x000000010d684b5d - [NSObject（NSObject）doesNotRecognizeSelector：] + 205 3 CoreFoundation 0x000000010d5d1e3a ___转发_ + 970 4 CoreFoundation 0x000000010d5d19e8 _CF_forwarding_prep_0 + 120 5 UIKit 0x000000010dc46257 - [UIApplication sendAction：to：from：forEvent：] + 125 6 UIKit 0x000000010dc461b2 - [UIApplication sendAction：toTarget：fromSender：forEvent：] + 79 7 UIKit 0x000000010dda1422 - [UIControl sendAction：to：forEvent：] + 67 8 UIKit 0x000000010dda16c6 - [UIControl _sendActionsForEvents：withEvent：] + 272 9 UIKit 0x000000010dda08a9 - [UIControl touchesEnded：withEvent：] + 599 10 UIKit 0x000000010dcacbe8 - [UIWindow _sendTouchesForEvent：] + 835 11 UIKit 0x000000010dcad7d6 - [UIWindow sendEvent：] + 865 12 UIKit 0x000000010dc62705 - [UIApplication sendEvent：] + 263 13 UIKit 0x000000010dc3f5df _UIApplicationHandleEventQueue + 6031 14 CoreFoundation 0x000000010d5a70f1 CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION + 17 15 CoreFoundation 0x000000010d59ceac __CFRunLoopDoSources0 + 556 16 CoreFoundation 0x000000010d59c363 __CFRunLoopRun + 867 17 CoreFoundation 0x000000010d59bd78 CFRunLoopRunSpecific + 488 18 GraphicsServices 0x0000000111fdebca GraphicsServices + 52170 19 UIKit 0x000000010dc4479b UIApplicationMain + 171 20 BottLED 0x000000010c7cb9ad main + 109 21 libdyld.dylib 0x000000011029ca05 libdyld.dylib + 10757 22 ??? 0x0000000000000001 0x0 + 1 ） libc ++ abi.dylib：以NSException类型的未捕获异常终止（LLDB）

当我执行一些断点并删除＆＃34; throws＆＃34;时，应用程序不会崩溃。我真的不知道该怎么做..我希望有人可以帮助我！

完整的代码是：

@IBAction func loginButtonPressed(sender: AnyObject)throws {
    var name:NSString = textFieldName.text!
    let pass:NSString = textFieldPw.text!
    if ( name.isEqualToString("") || pass.isEqualToString("") ) {
        let loginFailed = UIAlertView(title: "Failed to Signup",
            message: "Please fill in all Textfields",
            delegate: nil,
            cancelButtonTitle: "OK")
        loginFailed.show()
    } else {

            let post:NSString = "username=\(name)&password=\(pass)"

            NSLog("PostData: %@",post);

            let url:NSURL = NSURL(string: "my url")!

            let postData:NSData = post.dataUsingEncoding(NSASCIIStringEncoding)!

            let postLength:NSString = String( postData.length )

            let request:NSMutableURLRequest = NSMutableURLRequest(URL: url)
            request.HTTPMethod = "POST"
            request.HTTPBody = postData
            request.setValue(postLength as String, forHTTPHeaderField: "Content-Length")
            request.setValue("application/x-www-form-urlencoded", forHTTPHeaderField: "Content-Type")
            request.setValue("application/json", forHTTPHeaderField: "Accept")


            var reponseError: NSError?
            var response: NSURLResponse?

            var urlData: NSData?
            do {
                urlData = try NSURLConnection.sendSynchronousRequest(request, returningResponse:&response)
            } catch let error as NSError {
                reponseError = error
                urlData = nil
            }

            if ( urlData != nil ) {
                let res = response as! NSHTTPURLResponse!;

                NSLog("Response code: %ld", res.statusCode);

                if (res.statusCode >= 200 && res.statusCode < 300)
                {
                    let responseData:NSString  = NSString(data:urlData!, encoding:NSUTF8StringEncoding)!

                    NSLog("Response ==> %@", responseData);



                    let jsonData:NSDictionary = try NSJSONSerialization.JSONObjectWithData(urlData!, options:NSJSONReadingOptions.MutableContainers ) as! NSDictionary


                    let success:NSInteger = jsonData.valueForKey("success") as! NSInteger

                    //[jsonData[@"success"] integerValue];

                    NSLog("Success: %ld", success);

                    if(success == 1)
                    {

Answer 1

在Obj-C中throws是Obj-C error: (NSError **)error参数的语法糖。

将throws添加到方法时，它会秘密添加参数。您的方法将不再是loginButtonPressed:，它将是loginButtonPressed:error:（至少对于Obj-C）。但是，在处理事件时，系统仍将查找方法loginButtonPressed:，因为这是事件在XIB中的连接方式。该方法已不存在，因此该应用将与unrecognized selector sent to instance崩溃。

解决方案：不要在动作处理程序中使用throws，它违反了方法的约定，因为系统不会指望任何东西被抛出。捕获动作处理程序中的所有错误。

do {
    urlData = try NSURLConnection.sendSynchronousRequest(request, returningResponse:&response)
} catch let error as NSError {
    reponseError = error
    urlData = nil
} catch {
   // Catch all error-handling
    urlData = nil
}

Answer 2

没有什么能抓住这个错误。你需要从按钮IBAction中取出你的投掷方法。

从IBAction中删除throws并创建一个新方法。然后尝试捕获方法中的错误。无论哪种方式，都不要抛弃IBAction。

尝试 - 抛出IBAction - xCode 7

2 个答案: