I cloned the firebase chart app and added it to my project as a reference. Why does it work normally on the original file, but it keeps getting "Thread 1: Fatal error: Unexpectedly found nil while unwrapping an Optional value" when I clone it to my project The problem lies in this paragraph, I can't figure it out, can someone help me check it? This is ViewController

import UIKit

class User: NSObject {
    @objc var name: String?
    @objc var email: String?
    @objc var januaryE: NSNumber?
    @objc var febrauryE: NSNumber?
    @objc var marchE: NSNumber?
    @objc var aprilE: NSNumber?
    @objc var mayE: NSNumber?
    @objc var juneE: NSNumber?
    @objc var julyE: NSNumber?
    @objc var augustE: NSNumber?
    @objc var septemberE: NSNumber?
    @objc var octoberE: NSNumber?
    @objc var novemberE: NSNumber?
    @objc var decemberE: NSNumber?
    @objc var januaryS: NSNumber?
    @objc var febrauryS: NSNumber?
    @objc var marchS: NSNumber?
    @objc var aprilS: NSNumber?
    @objc var mayS: NSNumber?
    @objc var juneS: NSNumber?
    @objc var julyS: NSNumber?
    @objc var augustS: NSNumber?
    @objc var septemberS: NSNumber?
    @objc var octoberS: NSNumber?
    @objc var novemberS: NSNumber?
    @objc var decemberS: NSNumber?
    
    init(dictionary: [String: Any]) {
        self.name = dictionary["text"] as? String
        self.email = dictionary["email"] as? String
        self.januaryE = dictionary["januaryE"] as? NSNumber
        self.febrauryE = dictionary["febrauryE"] as? NSNumber
        self.marchE = dictionary["marchE"] as? NSNumber
        self.aprilE = dictionary["aprilE"] as? NSNumber
        self.mayE = dictionary["mayE"] as? NSNumber
        self.juneE = dictionary["juneE"] as? NSNumber
        self.julyE = dictionary["julyE"] as? NSNumber
        self.augustE = dictionary["augustE"] as? NSNumber
        self.septemberE = dictionary["septemberE"] as? NSNumber
        self.octoberE = dictionary["octoberE"] as? NSNumber
        self.novemberE = dictionary["novemberE"] as? NSNumber
        self.decemberE = dictionary["decemberE"] as? NSNumber
        self.januaryS = dictionary["januaryS"] as? NSNumber
        self.febrauryS = dictionary["febrauryS"] as? NSNumber
        self.marchS = dictionary["marchS"] as? NSNumber
        self.aprilS = dictionary["aprilS"] as? NSNumber
        self.mayS = dictionary["mayS"] as? NSNumber
        self.juneS = dictionary["juneS"] as? NSNumber
        self.julyS = dictionary["julyS"] as? NSNumber
        self.augustS = dictionary["augustS"] as? NSNumber
        self.septemberS = dictionary["septemberS"] as? NSNumber
        self.octoberS = dictionary["octoberS"] as? NSNumber
        self.novemberS = dictionary["novemberS"] as? NSNumber
        self.decemberS = dictionary["decemberS"] as? NSNumber
    }
}

CodePudding user response：

According to your screenshot, the value of user.januaryE was nil and you tried to unwrap it therefore the app crashes. Since you get data from somewhere and all properties are nil-able so you will need to either assign a default value for them as 0 (since it’s numberic type) or you ignore the nil values on your graph.