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ios - "uncaught exception"是什么？

转载 作者：行者123 更新时间：2023-11-28 10:56:49 27 4
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我正在尝试构建一个简单的 iPhone 应用程序，使用 UITextView 和 UIButton 将用户输入的文本保存到 iCloud。我从来没有做过这样的事情，所以我正在关注 this tutorial .到目前为止，他们的教程对我来说是完美无缺的，直到这一个。该应用程序构建良好，并在我的 iPhone 上运行，显示一个输入文本的位置，以及一个将文本保存到 iCloud 的按钮。但是当我点击屏幕输入文本时，应用程序崩溃并显示以下消息:

2017-03-24 08:45:56.093572 Gaethr2[6342:1419021] * 由于未捕获的异常“NSInvalidArgumentException”而终止应用程序，原因:“* -[NSMetadataQuery valueOfAttribute:forResultAtIndex:]:索引 (0) 越界 (0)'*** 首先抛出调用栈:(0x184b611b8 0x18359855c 0x184b61100 0x1855f1460 0x100056ffc 0x10005857c 0x184afab10 0x184afa214 0x184af9f90 0x184b69b8c 0x184a3be64 0x185570e0c 0x1855ef268 0x184afab10 0x184afa214 0x184af9f90 0x184b69b8c 0x184a3be64 0x185570e0c 0x1968d93e4 0x1968db29c 0x184b0ea44 0x184b0e240 0x184b0c094 0x184a3a2b8 0x1864ee198 0x18aa817fc 0x18aa7c534 0x10005b720 0x183a1d5b8)libc++abi.dylib:以 NSException 类型的未捕获异常终止来自调试器的消息:未能发送第 k 个数据包

这是 ViewController 代码:

import UIKit

class ViewController: UIViewController
{
    @IBOutlet weak var textView: UITextView!

    var document: MyDocument?
    var documentURL: URL?
    var ubiquityURL: URL?
    var metaDataQuery: NSMetadataQuery?



    func metadataQueryDidFinishGathering(notification: NSNotification) -> Void
    {
        let query: NSMetadataQuery = notification.object as! NSMetadataQuery

        query.disableUpdates()

        NotificationCenter.default.removeObserver(self,
                                                  name: NSNotification.Name.NSMetadataQueryDidFinishGathering,
                                                  object: query)

        query.stop()

        let resultURL = query.value(ofAttribute: NSMetadataItemURLKey,
                                    forResultAt: 0) as! URL

        if query.resultCount == 1 {
            let resultURL = query.value(ofAttribute: NSMetadataItemURLKey,
                                        forResultAt: 0) as! URL

            document = MyDocument(fileURL: resultURL as URL)

            document?.open(completionHandler: {(success: Bool) -> Void in
                if success {
                    print("iCloud file open OK")
                    self.textView.text = self.document?.userText
                    self.ubiquityURL = resultURL as URL
                } else {
                    print("iCloud file open failed")
                }
            })
        } else {
            document = MyDocument(fileURL: ubiquityURL!)

            document?.save(to: ubiquityURL!,
                           for: .forCreating,
                           completionHandler: {(success: Bool) -> Void in
                            if success {
                                print("iCloud create OK")
                            } else {
                                print("iCloud create failed")
                            }
            })
        }
    }



    override func viewDidLoad()
    {
        super.viewDidLoad()

        let filemgr = FileManager.default

        ubiquityURL = filemgr.url(forUbiquityContainerIdentifier: nil)

        guard ubiquityURL != nil else {
            print("Unable to access iCloud Account")
            print("Open the Settings app and enter your Apple ID into iCloud settings")
            return
        }

        ubiquityURL = ubiquityURL?.appendingPathComponent(
            "Documents/savefile.txt")

        metaDataQuery = NSMetadataQuery()

        metaDataQuery?.predicate =
            NSPredicate(format: "%K like 'savefile.txt'",
                        NSMetadataItemFSNameKey)
        metaDataQuery?.searchScopes =
            [NSMetadataQueryUbiquitousDocumentsScope]

        NotificationCenter.default.addObserver(self,
                                               selector: #selector(
                                                ViewController.metadataQueryDidFinishGathering),
                                               name: NSNotification.Name.NSMetadataQueryDidFinishGathering,
                                               object: metaDataQuery!)

        metaDataQuery!.start()
    }

    @IBAction func saveDocument(_ sender: AnyObject)
    {

        document!.userText = textView.text

        document?.save(to: ubiquityURL!,
                       for: .forOverwriting,
                       completionHandler: {(success: Bool) -> Void in
                        if success {
                            print("Save overwrite OK")
                        } else {
                            print("Save overwrite failed")
                        }
        })
    }

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


}

这是 MyDocument.Swift 的代码

import UIKit

class MyDocument: UIDocument
{
    var userText: String? = "Some Sample Text"

    override func contents(forType typeName: String) throws -> Any
    {
        if let content = userText
        {

            let length =
                content.lengthOfBytes(using: String.Encoding.utf8)
            return NSData(bytes:content, length: length)
        }
        else
        {
            return Data()
        }
    }

    override func load(fromContents contents: Any, ofType typeName: String?) throws
    {
        if let userContent = contents as? Data
        {
            userText = NSString(bytes: (contents as AnyObject).bytes,
                                length: userContent.count,
                                encoding: String.Encoding.utf8.rawValue) as? String
        }
    }
}

这是崩溃的屏幕截图:

enter image description here

感谢您的帮助!

27 4 0
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