Second variable takes the firsts value - swift

Question

I built an binary calculator app, For the numbers I have two variables. previousNumber and numberOnScreen. The idea is to convert the binary numbers to decimals, do the calculation and convert the answer back.
Lets say the first (previousNumber)number I pick is 1010 and the second (numberOnScreen) 10100
var numberOnScreen:Int = 0;
var previousNumber:Int = 0;
var doingMath = false
var operation = 0;
var decimal = 0;
var decimal1 = 0;
var binary:String = ""
var binary1:String = ""
#IBOutlet weak var label: UILabel!
#IBAction func Numbers(_ sender: UIButton) {
if doingMath == true
{
label.text = String(sender.tag-1)
numberOnScreen = Int(label.text!)!
doingMath = false
}
else
{
label.text = label.text! + String(sender.tag-1)
numberOnScreen = Int(label.text!)!
}
}
#IBAction func buttons(_ sender: UIButton) {
if label.text != "" && sender.tag != 6 && sender.tag != 8
{
previousNumber = Int(label.text!)!
binary = "\(previousNumber)"
decimal = Int(binary, radix: 2)!
binary1 = "\(numberOnScreen)"
decimal1 = Int(binary1, radix: 2)!
operation = sender.tag
doingMath = true;
}
else if sender.tag == 8
{
if operation == 3 //adding
{
print(previousNumber, numberOnScreen, decimal, decimal1)
It prints [ 1010, 10100, 10, 10 }
Any ideas why this is happening?

Answer 1

When you hit the = key, you need to update the calculation of decimal1. Move that code to the place where you are processing =:
#IBAction func buttons(_ sender: UIButton) {
if label.text != "" && sender.tag != 6 && sender.tag != 8
{
previousNumber = Int(label.text!)!
binary = "\(previousNumber)"
decimal = Int(binary, radix: 2)!
operation = sender.tag
doingMath = true;
}
else if sender.tag == 8
{
binary1 = "\(numberOnScreen)"
decimal1 = Int(binary1, radix: 2)!
if operation == 3 //adding
{
print(previousNumber, numberOnScreen, decimal, decimal1)
Also, I recommend that you get rid of the magic numbers in your code and replace them with constants. For your key tags, you could define a struct like this:
struct Key {
static let clear = 6
static let equals = 8
static let plus = 3
}
and then your code would read:
if label.text != "" && sender.tag != Key.clear && sender.tag != Key.equals {
which is much clearer.