如何通过按取消修复 Facebook 登录按钮中的崩溃

Question

出于教育目的，我正在尝试创建一个简单的应用程序来使用 Facebook 登录。

我没有使用 Cocoa Pods.

手动导入了 SD

这是我的应用委托中的代码：

import UIKit
import FBSDKCoreKit

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {
    var window: UIWindow?

    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
        FBSDKApplicationDelegate.sharedInstance().application(application, didFinishLaunchingWithOptions: launchOptions)
        return true
    }

    func application(_ application: UIApplication, open url: URL, sourceApplication: String?, annotation: Any) -> Bool {
        return FBSDKApplicationDelegate.sharedInstance().application(application, open: url, sourceApplication: sourceApplication, annotation: annotation)
    }

    func applicationDidBecomeActive(_ application: UIApplication) {
        FBSDKAppEvents.activateApp()
    }
}

在ViewController中，我声明了标签和 immageView，我将在其中输入从 facebook 下载的数据。在这一点上，我向您展示了 ViewController:

中编写的代码

import UIKit
import FBSDKCoreKit
import FBSDKLoginKit

class ViewController: UIViewController, FBSDKLoginButtonDelegate {
    @IBOutlet weak var lbl_fbid: UILabel!
    @IBOutlet weak var lbl_fbdirstname: UILabel!
    @IBOutlet weak var lbl_fblastname: UILabel!
    @IBOutlet weak var lbl_fbemail: UILabel!
    @IBOutlet weak var img_fbprofilepic: UIImageView!

    func loginButton(_ loginButton: FBSDKLoginButton!, didCompleteWith result: FBSDKLoginManagerLoginResult!, error: Error!) {

        if (error == nil) {
            print("Connected")
                        let r = FBSDKGraphRequest(graphPath: "me", parameters: ["fields":"email,first_name,last_name,picture.type(large)"], tokenString: FBSDKAccessToken.current()?.tokenString, version: nil, httpMethod: "GET")
                        r?.start(completionHandler: { (test, result, error) in
                        if let id : NSString = (result! as AnyObject).value(forKey: "id") as? NSString {
                            print("id: \(id)")
                            self.lbl_fbid.text = "ID: \(id)"
                        }
                            if let imageURL = (((((result! as AnyObject).value(forKey: "picture")) as AnyObject).value(forKey: "data")) as AnyObject).value(forKey: "url") as? NSString{
                            print("img url: \(imageURL)")
                            let url = URL(string: imageURL as String)
                            DispatchQueue.global().async {
                                let data = try? Data(contentsOf: url!)
                                DispatchQueue.main.async {
                                    self.img_fbprofilepic.image = UIImage(data: data!)
                                }
                            }
                        }
                        if let first_name : NSString = (result! as AnyObject).value(forKey: "first_name") as? NSString {
                            print("first_name: \(first_name)")
                            self.lbl_fbdirstname.text = "First_Name: \(first_name)"
                        }
                        if let last_name : NSString = (result! as AnyObject).value(forKey: "last_name") as? NSString {
                            print("last_name: \(last_name)")
                            self.lbl_fblastname.text = "First_Name: \(last_name)"
                        }
                        if let email : NSString = (result! as AnyObject).value(forKey: "email") as? NSString {
                            print("email: \(email)")
                            self.lbl_fbemail.text = "Email: \(email)"
                        }

                            if(error == nil)
                            {
                                print(result as Any)
                            }

                        })

        } else  {
            print(error.localizedDescription)
        }
    }

    func loginButtonDidLogOut(_ loginButton: FBSDKLoginButton!) {
        print("Disconnected")

            self.lbl_fbid.text = "ID: "
            self.lbl_fbdirstname.text = "First_Name: "
            self.lbl_fblastname.text = "First_Name: "
            self.lbl_fbemail.text = "Email: "
            self.img_fbprofilepic.image = nil
    }


    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view.

        let loginButton = FBSDKLoginButton()
        loginButton.readPermissions = ["public_profile", "email"]
        loginButton.center = self.view.center
        loginButton.delegate = self
        self.view.addSubview(loginButton)
    }
}

这里一切正常。我可以通过 facebook 登录，我可以用下载的数据填充标签和图像。

所以问题是另一个。如果碰巧，在登录过程中，我点击了应用程序崩溃的取消按钮，控制台给我这个：

Connected
libc++abi.dylib: terminating with uncaught exception of type NSException
(lldb)

我被重定向到 AppDelegate 中的这一行：

class AppDelegate: UIResponder, UIApplicationDelegate {

此消息为红色 "Thread 1: signal SIGABRT"。

Answer 1

我通过以这种方式构造函数 loginButton 来解决：

func loginButton(_ loginButton: FBSDKLoginButton!, didCompleteWith result: FBSDKLoginManagerLoginResult!, error: Error!) {
        if (error == nil) {
            if(result.isCancelled){
                print("login cancelled")
            }else{
                //code here
                print("Connected")
            }
        } else  {
            print(error.localizedDescription)
        }
    }

再见;)

如何通过按取消修复 Facebook 登录按钮中的崩溃

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