ios - 尝试在 iOS 7 中加载 Web View 时应用程序崩溃

Question

我正在使用 swift 2.2 并开发了一个具有表格 View 的应用程序。在特定行的水龙头上，我正在加载一个 WebView 。一切看起来都很完美，并且在运行 iOS 9 的 ipad 上完美运行。当我尝试加载相同的应用程序并尝试在 iOS 7 设备上加载 Web View 时，应用程序崩溃了。代码是

class AppCatalogViewController: UIViewController , UIWebViewDelegate {

var alertView = UIAlertView()

override func viewDidLoad() {
    super.viewDidLoad()
    NSLog("enetered the webView view controller")
    self.title = NSLocalizedString("mdm.agent.common.appCatalog", comment : "")
    self.view.autoresizesSubviews = true
    alertView = UIAlertView(title: NSLocalizedString("mdm.agent.common.loadingData", comment: ""), message: "", delegate: nil, cancelButtonTitle: nil, otherButtonTitles: "")
    let actInd : UIActivityIndicatorView = UIActivityIndicatorView(activityIndicatorStyle: UIActivityIndicatorViewStyle.WhiteLarge)
    actInd.startAnimating()
   actInd.frame = CGRectMake(125, 60, 37, 37)
    alertView.addSubview(actInd)
    //Change self.view.bounds to a smaller CGRect if you don't want it to take up the whole screen
    NSLog("setting the frame of the webview")
    let webView : UIWebView = UIWebView(frame: self.view.bounds)

    webView.autoresizingMask = UIViewAutoresizing.FlexibleWidth
    webView.scalesPageToFit = true
    webView.autoresizesSubviews = true
    webView.delegate = self



    let persist = Persistence()
    let url : String = "https://\(persist.getObject(mdmiosagent_Constants.SERVERNAMEKEY)):\(persist.getObject(mdmiosagent_Constants.SERVERPORTKEY))/showAppsList.mobapps?udid=\(persist.getObject(mdmiosagent_Constants.UDIDKEY))&isNativeAgent=true&authtoken=\(defaults.authToken)&SCOPE=\(defaults.scope)"

    let request : NSMutableURLRequest = NSMutableURLRequest(URL: NSURL(string: url)!)
    request.timeoutInterval = 10
    var userAgent : String = ""
    if(UIDevice.currentDevice().userInterfaceIdiom == UIUserInterfaceIdiom.Phone) {
        userAgent = "iPhone"
    } else {
        userAgent = "iPad"
    }

    request.setValue(userAgent, forHTTPHeaderField: "User-Agent")

    webView.loadRequest(request)

    self.view.addSubview(webView)
    alertView.show()

}

func webViewDidStartLoad(webView: UIWebView) {

}
func webViewDidFinishLoad(webView: UIWebView) {

    alertView.dismissWithClickedButtonIndex(-1, animated: true)
}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
}

func showError(error : NSString) {
    let alert : UIAlertView = UIAlertView(title: NSLocalizedString("mdm.agent.common.error", comment: ""), message: error as String, delegate: nil, cancelButtonTitle: "mdm.agent.common.okay", otherButtonTitles: "", "")
    alert.show()
}
// method to check authentication
func connection(connection: NSURLConnection, didReceiveAuthenticationChallenge challenge: NSURLAuthenticationChallenge) {

    if (challenge.protectionSpace.authenticationMethod == NSURLAuthenticationMethodServerTrust) {
        challenge.sender!.useCredential(NSURLCredential(forTrust: (challenge.protectionSpace.serverTrust!)), forAuthenticationChallenge: challenge)
    }
    challenge.sender?.continueWithoutCredentialForAuthenticationChallenge(challenge)
}

这在 iOS 9 设备上完美运行.. iOS 7 设备日志中显示的错误是

May 13 12:58:38 iPhone mdm.ios[1040] <Error>: *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '*** -[__NSArrayM insertObject:atIndex:]: object cannot be nil'
*** First throw call stack:
(0x2fc3bf83 0x3a3ecccf 0x2fb75f0d 0x328f21af 0x328f2f75 0x328f352b 0xdcd84 0xdce24 0x3245d4ab 0x3245d269 0x325e936b 0x32506d63 0x32506b6d 0x32506b05 0x32458d59 0x320d662b 0x320d1e3b 0x320d1ccd 0x320d16df 0x320d14ef 0x320cb21d 0x2fc07255 0x2fc04bf9 0x2fc04f3b 0x2fb6febf 0x2fb6fca3 0x34a75663 0x324bc14d 0xc1318 0x3a8f9ab7). 

谁能找出可能是什么原因？

Answer 1

我试过你的代码，效果很好。异常(exception)说:

[__NSArrayM insertObject:atIndex:]: object cannot be nil'

可能会出现，因为您尝试本地化一个字符串，例如，您的文件 Localizable.strings 已经存在但尚未本地化。

当您的应用程序的旧版本已启动到您的 iOS7 设备或模拟器设备时，就会发生这种情况，并且您重新运行新版本，但此未本地化的文件仍位于应用程序包的资源文件夹中。

当您构建一个新版本的应用程序时，未使用的文件不会被删除，因此最好的方法是从您的模拟器或真实设备中完全删除该应用程序，清除缓存并再次构建一个运行。

此外，正如您在评论中解释的那样，通过应用程序目录进行的更新情况导致了这种崩溃。避免这种情况的最好方法是使用 if let 或 guard 条件保护您的本地化。

从 iOS 7 开始，我相信您可以制作字符串文件 UTF-8 而不是 UTF-16。

来自official Apple doc :

Note: It is recommended that you save strings files using the UTF-8 encoding, which is the default encoding for standard strings files. Xcode automatically transcodes strings files from UTF-8 to UTF-16 when they’re copied into the product. For more information about the standard strings file format, see Creating Strings Resource Files. For more information about Unicode and its text encodings, go to http://www.unicode.org/ or http://en.wikipedia.org/wiki/Unicode.