如何在函数中初始化全局变量以在Swift中进一步使用？

Question

Thanks in advance for the help. I'm just starting out on swift and I'm using Xcode to to attempt at building a fairly simple app.

class ViewController: UIViewController {


    @IBOutlet var text: UITextField!
    @IBOutlet var Lable: UILabel!
    @IBOutlet var Button: UIButton!

    @IBOutlet var message1: UITextField!
    @IBOutlet var Button2: UIButton!

    var name = 0

    @IBAction func Button(sender: UIButton) {
         var name = text.text.toInt()
    }


    @IBAction func Button2(sender: UIButton) {

        var code = Array (message1.text).map{String($0).toInt()! }



        for var n = 0 ; n < code.count; n++
        {
            code[n] = code[n] + name
        }

        var StringArray = (code : String())

        if name != 0
        {
        message1.text = "name variable is inisialised"
        }

        else
        {
            message1.text = "Error name is not initialised"
        }

    }

When I try this out I always get the same answer that Name is not initialised as it still has the global inisialisation Name = 0 at the end but further down I initialise it to the int value whithin the text field yet it doesn't update the global variable. If You could give me some code to use to initialise name as a global variable and use it in the other functions That would be great. Thank you for your time!

Answer 1

One problem (not the only problem, as you'll later discover) is this:

var name = 0

@IBAction func Button(sender: UIButton) {
     var name = text.text.toInt() // this is a DIFFERENT "name"
}

You said var in the second one, which makes that name a different name - a local variable inside the function. Instead of using the global, you declared a different variable. In slightly more technical terms, you have redeclared this variable, overshadowing the global.

Answer 2

Change your Button() function to:

@IBAction func Button(sender: UIButton) {
  // Handle the case where toInt() fails, by returning nil/.None
  // For example, shown below, set name to `0`
  name = text.text.toInt() ?? 0
}

Also name is a particularly bad name to use when assigning it a number. Maybe name_index is better?