ios - 展开可选值/Swift 时意外发现 nil

Question

构建 ToDo 应用程序。创建新的待办事项任务时应用程序崩溃。

断点停止代码并返回:

Thread 1: Fatal error: Unexpectedly found nil while unwrapping an Optional value

 @IBAction func doneButton(_ sender: UIButton) {
    guard let title = textView.text, !title.isEmpty else {
        return
    }

    let todo = Todo(context: managedContext)
    todo.title = title
    todo.priority = Int16(segmentedControl.selectedSegmentIndex)
    todo.date = Date()

    do {
        try managedContext.save()
        dismiss(animated: true)
        textView.resignFirstResponder()

    } catch {
        print("Error saving todo: \(error)")

    }

}
@IBAction func cancelButton(_ sender: UIButton) {
    dismiss(animated: true)
    textView.resignFirstResponder() 
}

有什么可能导致应用程序崩溃的想法吗？谢谢

Answer 1

UISegmentedControlSegment 是公共(public)枚举，UISegmentedControl 是 UIControl根据您的评论，您似乎将 UISegmentedControl 误认为是 UISegmentedControlSegment，因此请按如下方式连接 UISegmentedControl:

@IBOutlet weak var segmentedControl: UISegmentedControl!