what's the difference between the value changed and editing changed event of UITextField

Question

I am currently reading a book about design patterns in swift, and there is a program that a method get notified when a stepper's value changed or a text field associated with it changed, here is the method

@IBAction func stockLevelDidChange(sender: AnyObject) {
    println("Method Trigged")
        if var currentCell = sender as? UIView {
            while (true) {
                currentCell = currentCell.superview!;
                if let cell = currentCell as? ProductTableViewCell {
                    if let id = cell.productID? {

                        var newStockLevel:Int?;

                        if let stepper = sender as? UIStepper {
                            newStockLevel = Int(stepper.value);
                        } else if let textfield = sender as? UITextField {
                            if let newValue = textfield.text.toInt()? {
                                newStockLevel = newValue;
                            }
                        }

                        if let level = newStockLevel {
                            products[id].4 = level;
                            cell.stockStepper.value = Double(level);
                            cell.stockField.text = String(level);
                        }
                    }
                    break;
                }
            }
            displayTotalStock();
        }
}

but I have some problems when change this thread of code, first when I just stripped out the while look, it just did not work.

@IBAction func stockLevelDidChange(sender: AnyObject) {
    println("Method Trigged")
        if var currentCell = sender as? UIView {
                currentCell = currentCell.superview!;
                if let cell = currentCell as? ProductTableViewCell {
                    if let id = cell.productID? {

                        var newStockLevel:Int?;

                        if let stepper = sender as? UIStepper {
                            newStockLevel = Int(stepper.value);
                        } else if let textfield = sender as? UITextField {
                            if let newValue = textfield.text.toInt()? {
                                newStockLevel = newValue;
                            }
                        }

                        if let level = newStockLevel {
                            products[id].4 = level;
                            cell.stockStepper.value = Double(level);
                            cell.stockField.text = String(level);
                        }
                    }
                    break;
            }
            displayTotalStock();
        }
}

and also, when I changed the text field's event from editing changed to value changed, it just don't work too!!!

anyone knows what's going on there, thanks

Answer 1

Editing change is the textField statu. Value Changed is textField content has changed.

if you want do some operation, you can use

Such:

[textField addTarget:self action:@selector(textFieldAction:) forControlEvents:UIControlEventValueChanged];

you can change Control Event for your target. Action. Thanks.

Answer 2

From Apple's UIControl Control Events docs:

UIControlEventValueChanged
A touch dragging or otherwise manipulating a control, causing it to emit a series of different values.

UIControlEventEditingChanged
A touch making an editing change in a UITextField object.