Question

这个IBAction带来了一个带有两个文本框的UIAlertController。一个名字的盒子和一个年龄的盒子。我正在尝试这样做，以便用户不必输入他们的年龄，如果他们不想。现在，如果他们没有进入他们的年龄，应用程序就会被person.age = Int16(points!)!行崩溃说“线程1：致命错误：在解开一个Optional值时意外发现nil”。我试图使用if else语句来阻止它。我错过了什么？

   @IBAction func addRowBtn(_ sender: Any) {
        let alert = UIAlertController(title: "Add Person", message: nil, preferredStyle: .alert)
        alert.addTextField { (textField) in
            textField.placeholder = "Task"
        }
        alert.addTextField { (textField) in
            textField.placeholder = "Points"
            textField.keyboardType = .numberPad
        }
        let action = UIAlertAction(title: "post", style: .default) { (_) in
            let name = alert.textFields?.first!.text!
            let age = alert.textFields?.last!.text!
            if name != nil && age != nil {
                let person = Person(context: PersistenceServce.context)
                person.name = name
                person.age = Int16(age!)!
                PersistenceServce.saveContext()
                self.people.append(person)
                self.table.reloadData()

            }
             if name != nil && age == nil {
                let person = Person(context: PersistenceServce.context)
                person.name = name
                person.age = 0
                PersistenceServce.saveContext()
                self.people.append(person)
                self.table.reloadData()
            }
        }
        alert.addAction(action)
        present(alert, animated: true, completion: nil)
    }
}

Answer 1

为了避免解开问题，我建议你这样做：

let action = UIAlertAction(title: "post", style: .default) { (_) in
        if let ageString = alert.textFields?.last?.text,
            let age = Int16(ageString),
            let name = alert.textFields?.first?.text {
            let person = Person(context: PersistenceServce.context)
            person.name = name
            person.age = age
            PersistenceServce.saveContext()
            self.people.append(person)
            self.table.reloadData()
        } else if let name = alert.textFields?.first?.text {
            let person = Person(context: PersistenceServce.context)
            person.name = name
            person.age = 0
            PersistenceServce.saveContext()
            self.people.append(person)
            self.table.reloadData()
        }
}

Int16找到了nill

1 个答案: