Counting the amount of selected buttons in a swift array

Question

I have 4 custom-made toggle buttons. Users can select multiple buttons and toggle the same button, however, there must always be at least 1 selected button.

If 1 out of 4 buttons are selected, then the selected button can not be toggled to become deselected.

I am looking for a way to determine this logic. My thought was to simply count the selected items in the button array, and if there is only 1 selected, then escape via return.

Here's my progress

func toggleButton(button: ToggleButton){
    
    let buttonArray = [btn1, btn2, btn3, btn4]
    for btn in buttonArray{
        // Count the amount of selected buttons in buttonArray
        // if 1, return.
    }
    
    button.isSelected = !button.isSelected
}

Is there a way to count the amount of selected buttons in buttonArray?

Answer 1

Maybe a variable numberOfSelected to keep track of the number of selected buttons? And if it's equal to 1, return:

var numberOfSelected = 0
let buttonArray = [btn1, btn2, btn3, btn4]
for btn in buttonArray {
    if btn.isSelected {
        numberOfSelected += 1
    }
}
if numberOfSelected == 1 { return } /// escape via return