Swift中未捕获的错误/异常处理

Question

我知道Cocoa中有一个UncaughtExceptionHandler，但我正在为Swift寻找同样的东西。即每当应用程序中由于任何错误而未在本地捕获任何错误/异常时，它应该一直冒泡到顶级应用程序对象，在那里我应该能够优雅地处理它并适当地响应用户。Android拥有它。Flex有它。Java有它。想知道Swift为什么缺少这个关键功能。

Answer 1

这是我用来记录所有异常/错误的代码。Log.error(with:)是一个自定义函数，我存储堆栈跟踪以及其他信息。Thread.callStackSymbols是一个字符串数组，表示堆栈跟踪。

func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]? = nil) -> Bool {

    NSSetUncaughtExceptionHandler { exception in

        Log.error(with: Thread.callStackSymbols)

    }

    signal(SIGABRT) { _ in

        Log.error(with: Thread.callStackSymbols)

    }

    signal(SIGILL) { _ in

        Log.error(with: Thread.callStackSymbols)

    }

    signal(SIGSEGV) { _ in

        Log.error(with: Thread.callStackSymbols)

    }

    signal(SIGFPE) { _ in

        Log.error(with: Thread.callStackSymbols)

    }

    signal(SIGBUS) { _ in

        Log.error(with: Thread.callStackSymbols)

    }

    signal(SIGPIPE) { _ in

        Log.error(with: Thread.callStackSymbols)

    }

    return true

}

Answer 2

enter code here

导入UIKit导入CoreData

class ViewController：UIViewController {

@IBOutlet weak var lgnusername: UITextField!

@IBOutlet weak var lgnpassword: UITextField!

var result = NSArray（）

override func viewDidLoad() {

    super.viewDidLoad()

    // Do any additional setup after loading the view, typically from a nib.

}

@IBAction func loginaction(_ sender: Any)

{

    let app = UIApplication.shared.delegate as! AppDelegate

    let context = app.persistentContainer.viewContext

    let request = NSFetchRequest<NSFetchRequestResult>(entityName: "Login")

    let searchString = self.lgnusername.text

    let searcghstring2 = self.lgnpassword.text

    request.predicate = NSPredicate (format: "username == %@", searchString!)

    do

    {

        let result = try context.fetch(request)

        if result.count > 0

        {

            let   n = (result[0] as AnyObject).value(forKey: "username") as! String

            let p = (result[0] as AnyObject).value(forKey: "userpassword") as! String

             print("p,n",n,p)

            if (searchString == n && searcghstring2 == p)

            {

                let UserDetailsVc = self.storyboard?.instantiateViewController(withIdentifier: "userViewController") as! userViewController

                //UserDetailsVc.myStringValue = lgnusername.text

                self.navigationController?.pushViewController(UserDetailsVc, animated: true)

            }

            else if (searchString == n || searcghstring2 == p)

            {

                // print("password incorrect ")

                let alertController1 = UIAlertController (title: "no user found ", message: "password incorrect ", preferredStyle: UIAlertControllerStyle.alert)

                alertController1.addAction(UIAlertAction(title: "OK", style: .default, handler: nil))

                present(alertController1, animated: true, completion: nil)

            }

        }

        else

        {

            let alertController1 = UIAlertController (title: "no user found ", message: "invalid username ", preferredStyle: UIAlertControllerStyle.alert)

            alertController1.addAction(UIAlertAction(title: "OK", style: .default, handler: nil))

            present(alertController1, animated: true, completion: nil)

            print("no user found")

        }

    }

    catch

    {

        print("error")

    }

}

}