使用UserDefaults保存和检索bool [英] Saving and retrieving a bool with UserDefaults

问题描述

我正在尝试从UISwitch将 bool 值保存到UserDefaults，并在另一个视图中检索它。但是，我尝试过多个教程和堆栈答案，似乎没有工作。

I'm trying to save a bool value to UserDefaults from a UISwitch, and retrieve it in another view. However, I've tried following multiple tutorials and stack answers and none seem to work.

这就是我保存它的方式：

This is how I'm saving it:

class SettingsViewController: UITableViewController {

@IBOutlet weak var soundSwitchOutlet: UISwitch!

@IBAction func soundSwitch(_ sender: UISwitch) {

    UserDefaults.standard.set(soundSwitchOutlet.isOn, forKey: "sound")

}

这就是我试图在另一个视图中检索它的方式：

and this is how I'm trying to retrieve it in another view:

if let savedValue = UserDefaults.standard.bool(forKey: "sound") {
        boolValue = savedValue
    }

//this is inside viewDidLoad and "boolValue" was declared outside viewDidLoad//

出于某种原因，这段代码给了我错误，而且我尝试过的东西都没有。如何将bool保存到UserDefaults并在另一个视图中检索？

For a reason this code is giving me errors and none of the things I've tried have worked. How can I save a bool to UserDefaults and retrieve it in another view?

编辑：我想我修复了第一部分。但是，我检索布尔值的方式似乎完全错误。另外：没有其他的stackExchange答案回应我的要求，至少不是在swift中。

I think I fixed the first part. However, the way I'm retrieving the boolean seems to be totally wrong. Also: No other stackExchange answer responds to what I'm asking, at least not in swift.

推荐答案

正如Leo在注释 bool（forKey 返回非可选 Bool 。如果密钥不存在 false 已退回。

As Leo mentioned in the comments bool(forKey returns a non-optional Bool. If the key does not exist false is returned.

所以它只是

boolValue = UserDefaults.standard.bool(forKey: "sound")

致电<$ c $不需要其他答案中建议的c> synchronize（）。框架会定期更新用户默认数据库。

Calling synchronize() as suggested in other answers is not needed. The framework updates the user defaults database periodically.

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