UISegmentedControl and .selectedSegmentIndex wrong values? - ios

Question

I have a simple Segment in my code with 3 elements. For testing purposes I also do have a variable that increments based on which of the segments I press (3). The value of that variable is printed in a UITextView. This is the code:
import UIKit
class ViewController: UIViewController
{
#IBOutlet weak var segment: UISegmentedControl!
#IBOutlet weak var prwtoView: UIView!
#IBOutlet weak var prwtoText: UITextField!
var i : Int = 0
override func viewWillAppear(animated: Bool)
{
prwtoText.backgroundColor = UIColor.purpleColor()
prwtoText.textColor = UIColor.whiteColor()
segment.setTitle("Zero", forSegmentAtIndex: 0)
segment.addTarget(self, action: "action", forControlEvents: .ValueChanged)
segment.insertSegmentWithTitle("random", atIndex: 2, animated: false)
}
func action()
{
let argumentForSegment = segment.selectedSegmentIndex
if argumentForSegment == 0
{
i = 0
}
if argumentForSegment == 1
{
i += 2
}
else
{
i += Int(arc4random_uniform(100))
}
print(argumentForSegment)
prwtoText.text = "\(i)"
}
}
While I know that it starts with value -1 i don't want my app to do anything if not pressed. The thing is that even when I press the first segment (0) and it is supposed to make i = 0 it doesn't do that, although if I print argumentForSegment in my terminal it does show the 0 as value. Concluding, every time I press the zero segment (0), my i value won't become 0. Perhaps I am using the wrong method from UISegmentedControl?
edit: Got it fixed by changing the following code:
func action()
{
let argumentForSegment = segment.selectedSegmentIndex
if argumentForSegment == 0
{
i = 0
}
if argumentForSegment == 1
{
i += 2
}
else
{
i += Int(arc4random_uniform(100))
}
print(argumentForSegment)
prwtoText.text = "\(i)"
}
to:
func action()
{
let argumentForSegment = segment.selectedSegmentIndex
if argumentForSegment == 0
{
i = 0
}
if argumentForSegment == 1
{
i += 2
}
else if argumentForSegment == 2 // <==== here
{
i += Int(arc4random_uniform(100))
}
print(argumentForSegment)
prwtoText.text = "\(i)"
}
Could someone explain why it used the priority of else although the value was zero when printing argumentForSegment? In other words why when I had an else alone for the value of argumentForSegment == 0 it chose the else instead of the first statement?

Answer 1

Could someone explain why it used the priority of else although the
value was zero when printing argumentForSegment? In other words why
when I had an else alone for the value of argumentForSegment == 0 it
chose the else instead of the first statement?
When you have a situation where the code is not behaving as you expect, it is helpful to step through it in the debugger, or add some diagnostic print statements.
For example:
func action()
{
let argumentForSegment = segment.selectedSegmentIndex
if argumentForSegment == 0
{
print("In first block")
i = 0
}
if argumentForSegment == 1
{
print("In second block")
i += 2
}
else
{
print("In third block")
i += Int(arc4random_uniform(100))
}
print(argumentForSegment)
prwtoText.text = "\(i)"
}
If you do this, you will notice that when argumentForSegment is 0, the output will be:
In first block
In third block
So, the problem is not that it is choosing the third block over the first. The problem is that it is doing both. You want it to stop after it has detected that argumentForSegment is 0, so add an else to the second conditional statement so that it only does that when the first conditional statement failed:
func action()
{
let argumentForSegment = segment.selectedSegmentIndex
if argumentForSegment == 0
{
i = 0
}
else if argumentForSegment == 1 // added "else" here
{
i += 2
}
else
{
i += Int(arc4random_uniform(100))
}
print(argumentForSegment)
prwtoText.text = "\(i)"
}

Answer 2

To improve on Vacawama's answer, you can format this much easier by using a switch statement:
func action() {
let argumentForSegment = segment.selectedSegmentIndex
switch argumentForSegment {
case 0:
i = 0
case 1:
i += 1
case 2:
i += Int(arc4random_uniform(100))
default:
break
}
print(argumentForSegment)
prwtoText.text = "\(i)"
}
it's much more clean for this type of thing.
(thanks, vacawama)