将label.text保存在swift4中

Question

Im currently developing a iOS app in which im going to keep track of our warehouse stock. It's a pretty simple app an just contains a lable and an stepper. The app is pretty much finished, but i don't get how to save the changed value of the label. I want to save it automatically so that when someone presses the "+" on the stepper, the value should save without pressing a extra save button

Current code:

//montageplatte
@IBOutlet weak var lbl_montageplatte: UILabel!
@IBAction func stepper_montageplatte(_ sender: UIStepper)
{
    lbl_montageplatte.text = Int(sender.value).description
}

Answer 1

you can save it in UserDefaults .

@IBAction func stepper_montageplatte(_ sender: UIStepper) {
    lbl_montageplatte.text = Int(sender.value).description

    UserDefaults.standard.set(String(sender.value), forKey: "lblMontageplatte")
}

To get back value you can do as follow...

if let lblValue = UserDefaults.standard.object(forKey: "lblMontageplatte") as? String {

   print(lblValue)
   lbl_montageplatte.text = lblValue
}

Answer 2

Simple solution:

In the custom cell create an outlet for the stepper and a NSKeyValueObservation property

@IBOutlet weak var stepper : UIStepper!
var stepperObservation : NSKeyValueObservation?

In cellForRow in the controller add the key value observer

cell.stepperObservation = cell.stepper.observe(\.value, options: [.new]) { (stepper, change) in
    print(change.newValue!)
}

Rather than printing the new value update the model (the item for the particular index path) and save the datasource array if necessary.