Making Types in Swift Floating Point Value and "X": Polloquin Exercise Notation

Question

I am trying to code times for weightlifting. There are four phases to a repetition:

Eccentric (Time spent lowering the weight) Bottom (Time spent at the bottom of the lift) Concentric (Time spent lifting the weight) Top (Time spent a the top of the lift)

It will be formatted like this: 1030

so in that example, a person would take 1 second lowering the weight, then immediately lift the weight taking three seconds, reach the end of the movement and stop to complete one repetition.

class rep {

    var eccentric:Float //  time spent lowering the weight
    var bottom:Float // time spent at the bottom of the repetition.
    var concentric:Float  // time spent raising the weight.
    var top:Float // time spent at the top of the repetition.

    var notation:String

    init(timeDown:Float, timeBottom:Float, timeUp:Float, timeTop:Float)        {

    eccentric = timeDown
    bottom = timeBottom
    concentric = timeUp
    top = timeTop

    notation = "\(eccentric),\(bottom),\(concentric),\(top)"

}

func displayNotation() -> String{

    print(notation)

    return notation

    }

}





class ViewController: UIViewController {

override func viewDidLoad() {
    super.viewDidLoad()


   let repetition = rep(timeDown: 1,timeBottom: 0,timeUp: 3,timeTop: 0)

  repetition.displayNotation()



}

this outputs 1.0,0.0,3.0,0.0

What I want to do is have an additional character "X" to indicate "as fast as possible." I am thinking that I would need to create a new type for this? So I want to be able to accept a float or that particular character... totally baffled as to how to go about this.

Thanks for any response

Answer 1

Ok, so this is one way to go about it.

First create a model for your data:

class Data {
    var string: String
    var value: Double?

    init(string: String, value: Double?) {
        self.string = string
        self.value = value
    }
}

The string will be used for displaying, and the value will be used for calculations. I set the value as an optional which will be explained in a moment.

---

Then create a data source for the UIPickerView and populate it:

var dataSource: [Data] = []

// Adds all values from 0.0 to 9.9 and the "additional character".
func populateDataSource() {
    for i in 0..<100 {
        let value = Double(i) / 10
        dataSource.append(Data(string: value.description, value: value))
    }
    dataSource.append(Data(string: "X", value: nil))
}

What I've done here is set the value for the additional character to nil.

---

Assuming you've already configured your UIPickerView, add the UIPickerViewDataSource methods:

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

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

func pickerView(pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {
    return dataSource[row].string
}

// This variable will be used to hold the user selection.
var selected: Data?

// If you want it to default to e.g. 0.0, just create it as:
// var selected = dataSource.first

func pickerView(pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {
    self.selected = dataSource[row]
}

---

And now you can do your calculations based on the selection:

// You should check that selection isn't nil before doing this.
// Depends on how you create it.

if let value = selection.value {
    // The selection has a value between 0.0 and 9.9.
    // So, do your standard calculations for that.
} else {
    // The selection does not have a value, which means it's your custom character.
    // So, take that into account in your calculations.
}