如何将UISlider的当前值快速保存到我的NSUserDefaults中？

Question

I have an app with two settings components, a uiSlider and a uiSwitch .

I know how to save option for the switch, this is what I'm doing:

@IBOutlet weak var settingA: UISwitch!

override func viewDidLoad() {

        settingA.on = NSUserDefaults.standardUserDefaults().boolForKey("settingA")
...
}

@IBAction func saveSettingA(sender: AnyObject) {
    print("setting A changed")
    NSUserDefaults.standardUserDefaults().setObject(settingA.on, forKey: "settingA")
    NSUserDefaults.standardUserDefaults().synchronize()
}

Now I want to do the same for the slider. I already created an outlet to the slider and to the label next to it (that shows the value of the slider):

@IBOutlet weak var sliderLabel: UILabel!
@IBOutlet weak var sliderSlider: UISlider!

and also I have a method for updating the label every time user moves the slider around:

@IBAction func sliderValueChanged(sender: UISlider) {
    var currentValue = Int(sender.value)
    sliderLabel.text = "\(currentValue)"
}

But how can I save it to the NSUserDefaults every time user chooses new value?

Answer 1

I'd suggest you connect/add your/another action via Storyboard in this way:

Special stress here is that you should really only store the value once the user releases the button (otherwise you would redundantly make store requests to NSUserDefaults , which I'm sure you don't want), hence you can see I selected Touch Up Outside instead of Value Changed for the event. The reason I phrased it like this ("connect/add your/another") is because you can connect multiple @IBAction s, for example one for the event Value Changed for when you want to observe the value changing and doing something when that happens and also as I demonstrated to act upon the user letting go of the slider.

Then, in order to store the value, you can do:

@IBAction func valueChangeEnded(slider: UISlider) {
    print("save to user defaults")
    NSUserDefaults.standardUserDefaults().setFloat(slider.value, forKey: "slider_value")
  }

And read it back in like this:

let sliderValue = NSUserDefaults.standardUserDefaults().floatForKey("slider_value")

Answer 2

You should be able to use the same logic in saveSettingA inside of the sliderValueChanged function. Just save the sender.value object rather than the int value.

Answer 3

swift 4.2

1.In your view will appear.

fontSlider.setValue(UserDefaults.standard.float(forKey: "slider_value"), animated: false)

2.Take another outlet from storyBoard as "editingDidEnd". In that function:

UserDefaults.standard.set(fontSlider.value, forKey: "slider_value")

3.And finally in your ValueChanged Outlet.

UserDefaults.standard.set(fontSlider.value, forKey: "slider_value")