SWIFT-'double'不能转换为'string'

Question

I am learning the Swift language and I want to make a label equal what the PickerView has selected. I am making a countdown timer to learn the language and to learn about timing with the NSTimer. I am trying to convert the number, which is a double, to a string, which would be the UILabel.

This is what I have for the PickerView. //UIPickerView

var numbers = [1.00, 2.00, 3.00, 4.00, 5.00, 6.00, 7.00,8.00, 9.00, 10.00, 11.00,12.00, 13.00, 14.00, 15.00, 16.00, 17.00, 18.00, 19.00, 20.00]


func numberOfComponentsInPickerView(pickerView: UIPickerView) -> Int {
    return 1
}

func pickerView(pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
    return numbers.count
}

func pickerView(pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String! {
    return numbers[row]
}

func pickerView(pickerView: UIPickerView!, didSelectRow row: Int, inComponent component: Int){

    subtractNumbers(\(numbers))

}

func subtractNumbers(number: Double) -> Double {
    return number - 0.01
}

I have researched a little bit and I am pretty sure I have to format it somehow. Any help is appreciated. Please explain your answers!

Answer 1

Issue is with the following function:

func pickerView(pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String!
{
    return numbers[row]
}

The return type of thee function in String but you are returning a Double .

Change it like:

func pickerView(pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String!
{
    return "\(numbers[row])";
}

Also there is one more issue in your following code:

func pickerView(pickerView: UIPickerView!, didSelectRow row: Int, inComponent component: Int)
{
    subtractNumbers(\(numbers))
}

You are passing an entire array instead of selected value. So change the code like:

func pickerView(pickerView: UIPickerView!, didSelectRow row: Int, inComponent component: Int)
{
    subtractNumbers(numbers[row])
}

Answer 2

This is how you convert a number to a string.

var number = 1.0
var string = "\(number)"