Application is crashing on facebook in apple review - ios

Question

We were unable to review your app as it crashed on launch. We have attached detailed crash logs to help troubleshoot this issue.
Specifically, your app still crashed on launch after the user logged in with facebook.
I m unable to catch the crash or any error.
Here's the code for where I think it's crashing (run right after users log in with Facebook)
#IBAction func Btn_facebook(_ sender: Any)
{
getFacebookUserInfo()
}
func getFacebookUserInfo()
{
let fbLoginManager : FBSDKLoginManager = FBSDKLoginManager()
fbLoginManager.logIn(withReadPermissions: ["public_profile","email"], from: self) { (result, error) -> Void in
if (error == nil)
{
let fbloginresult : FBSDKLoginManagerLoginResult = result!
// if user cancel the login
if (result?.isCancelled)!{
return
}
if(fbloginresult.grantedPermissions.contains("email"))
{
self.getFBUserData()
self.fbtoken = result!.token.tokenString
}
}
}
}
func getFBUserData()
{
if((FBSDKAccessToken.current()) != nil)
{
FBSDKGraphRequest(graphPath: "me", parameters: ["fields": "id, name, email, picture"]).start(completionHandler: { (connection, result, error) -> Void in
if result != nil {
guard FBSDKAccessToken.current().tokenString != nil else {
debugPrint("failed to get access token")
return
}
guard let result = result as? NSDictionary, let user_id_fb = result["id"] as? String else {
print("error")
return
}
}
if (error == nil)
{
let fbDetails = result as! NSDictionary
let field = result! as? [String:Any]
if let imageURL = ((field!["picture"] as? [String: Any])?["data"] as? [String: Any])?["url"] as? String {
print(imageURL)
let url = URL(string: imageURL)
print(url!)
self.fburl = imageURL
print(self.fburl!)
}
let checkemail = fbDetails["email"] as? String
if(checkemail != nil)
{
print(" check email not nil ", checkemail as Any)
self.fbemail = (fbDetails["email"] as? String)
self.fbid = (fbDetails["id"] as? String)
self.fbname = (fbDetails["name"] as? String)
self.GandfLogin(name: self.fbname!, email: self.fbemail!, post_image: (self.fburl!))
}
else
{
print(" check email nil ",checkemail ?? String.self)
self.fbid = (fbDetails["id"] as? String)
self.fbname = (fbDetails["name"] as? String)
self.GandfLogin(name: self.fbname!, email: self.fbid!, post_image: (self.fburl!))
}
}
else
{
print(error?.localizedDescription ?? "Not found")
}
})
}
}

Answer 1

Use soft unwraps instead of ! in most cases
Because it can lead to crashes if Facebook does not send data which you a looking for back
Do it this way:
guard let fbDetails = result as NSDictionary else {
//Show error to user or something else
return
}