Having trouble taking input from textField for measurement conversion value, get various errors

Question

I am trying to add a basic conversion method using if statements and two pickerViews. For example, I'm trying to convert say "inches" to "feet" or "millimeters" but when I try and use the textField as input in the conversion initialization I get different errors like:

Something like "cannot convert type String or Double to expected type BinaryInteger Cannot assign to property: 'self' is immutable

So far I have tried the following and many more:

var fromInches = Measurement(value: Double(exactly: BinaryInteger(convertInput.text)), Double, unit: UnitLength.inches)

var fromInches = Measurement(value: Double(convertInput.text), Double, unit: UnitLength.inches)

Full code (excluding unnecessary):

    import UIKit

class MetricImperialConvertViewController: UIViewController, UIPickerViewDelegate, UIPickerViewDataSource {

    @IBOutlet weak var convertFrom: UIPickerView!
    @IBOutlet weak var convertTo: UIPickerView!
    
    @IBOutlet weak var convertInput: UITextField!
    @IBOutlet weak var convertOutput: UITextView!
    
    var selectedFromUnit = ""
    var selectedToUnit = ""
    
    // Convert from picker tag is #1
    var convertFromData = ["Inches", "Feet", "Millimeters", "Centimeters", "Meters"]
    //Convert to picker tag is #2
    var convertToData = ["Inches", "Feet", "Millimeters", "Centimeters", "Meters"]
    ...

        func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {
        if pickerView.tag == 1 {
        selectedFromUnit = convertFromData[row]
        } else if pickerView.tag == 2 {
        selectedToUnit = convertToData[row]
        }
        
        print("Convert from: \(selectedFromUnit)\n to: \(selectedToUnit)")
        
        // Convert inches to feet
        if selectedFromUnit == "inches" && selectedToUnit == "feet" {
            var fromInches = Measurement(value: Double(convertInput.text), Double, unit: UnitLength.inches)
            convertOutput.text = fromInches.converted(to: UnitLength.feet)
            
        }
        
    }

This thing is driving me nuts, I'm way too new at code to deal with ultra complexity. Please help :)

`BinaryInteger` is a protocol not a type. You should use `Int`. Note that value expects a Double so there is no need to convert the value to integer. `var fromInches = Measurement(value: Double(convertInput.text!) ?? .zero, unit: .inches)` — Leo Dabus, Aug 01 '20 at 02:14
Btw why are you using textview? You probably want a textfield. — Leo Dabus, Aug 01 '20 at 02:25
Leo your code solves the first line errors but then the second line of the conversion throws: Cannot assign value of type '()' to type 'String'... I am confused, am i not understanding the Measurement method or is this a problem with the textField? ... I am using the textView for the unit conversion output and the textFeild for the unit value to be converted — RobbB, Aug 01 '20 at 02:53
Do you need a textview? Is it editable? You can use a multi line label — Leo Dabus, Aug 01 '20 at 03:08
You're right I could use a label but that doesn't fix the problem leading up to displaying the result of converting two values. Any other time I've gotten user input via a textField and inserted it into a method there was no issue. Now the "Measurement" is giving trouble... — RobbB, Aug 01 '20 at 03:18
if you need to properly format the resulting value you can check this post https://stackoverflow.com/a/39860810/2303865 — Leo Dabus, Aug 01 '20 at 03:39
I think that fixed it all. Now i find that my code does not do what i wanted. Back to the drawing board. Thanks for the help :) — RobbB, Aug 01 '20 at 03:49

score 0 · Answer 1 · answered Aug 02 '20 at 00:49

I must have been very tired yesterday because i spotted my error today and I wanted to post the answer just in case someone else needs the code:

Basically my string inputs in the condition of the "IF" statement was missing capitol first letter... ;)

    func convert() {
    // Convert inches to feet
    if selectedFromUnit == "Inches" && selectedToUnit == "Feet" {
        let value = Double(convertInput.text!)!
        let fromInches = Measurement(value: value, unit: UnitLength.inches)
        let result = fromInches.converted(to: UnitLength.feet)
        print("\(result)")
    } else {
        print("nil")
        print("\(selectedFromUnit) to \(selectedToUnit)")
    }
}

Having trouble taking input from textField for measurement conversion value, get various errors

1 Answers1