3

I have implemented an NSMeasurementFormatter and am having an odd issue. When the app is loaded as en_US, I get all my weights loaded into the text boxes as pounds, brilliant. However when I switch my app to en_GB and load the same data, i get nothing appearing in the text boxes.

When i print the objects the print out states the weights in kg so they are converting correctly, but they arent loading into the actual text boxes to be visible to the user.

Is there any clear cause to this? I have spent a few hours trying to work out why it works for one location but not the other! Appreciate the insight, here is the code:

Here is the initial save of an exercise where it either goes one way ot another depending on the apps setup at this point

        if self.localeIdentifier == "en_GB" {
            let kgWeight = Measurement(value: Double(self.userExerciseWeight.text!)!, unit: UnitMass.kilograms)
            newUserExercise.weight = kgWeight as NSObject?
            newUserExercise.initialMetricSystem = self.localeIdentifier
            print("SAVED AS \(localeIdentifier) METRIC")
        } else if self.localeIdentifier == "en_US" {
            let lbsWeight = Measurement(value: Double(self.userExerciseWeight.text!)!, unit: UnitMass.pounds)
            newUserExercise.weight = lbsWeight as NSObject?
            newUserExercise.initialMetricSystem = self.localeIdentifier
            print("SAVED AS \(localeIdentifier) IMPERIAL")
        }

Then here is my attempt to later reload this objects weight property 

   let formatter = MeasurementFormatter()
    let exerciseWeight = userExercise.weight as! Measurement<Unit>
    let localeIdentifier = UserDefaults.standard.object(forKey: "locale")
    let locale = Locale(identifier: localeIdentifier as! String)
    formatter.locale = locale
    let numberFormatter = NumberFormatter()
    numberFormatter.maximumFractionDigits = 2
    formatter.numberFormatter = numberFormatter

    let finalWeight = formatter.string(from: exerciseWeight)
    cell.todaysExerciseWeightLabel.text = finalWeight 
}

So when set to US, i get a pounds readout to 2 decimal places, but when i set to GB i get nothing visible, i can just see it did the conversion in the print out of the object, pics below of the console that shows for loading both routines, and shots of the results:

enter image description here

enter image description here

enter image description here

UPDATED BELOW WITH MASSFORMATTER INFO

    let localeIdentifier = UserDefaults.standard.object(forKey: "locale") as! Locale
    let exerciseWeight = userExercise.weight as! Measurement<Unit>
    let formatter = MassFormatter()
    formatter.numberFormatter.locale = localeIdentifier
    formatter.numberFormatter.maximumFractionDigits = 2

    if localeIdentifier.usesMetricSystem {
        let kgWeight = exerciseWeight.converted(to: .kilograms)
        let finalKgWeight = formatter.string(fromValue: kgWeight.value, unit: .kilogram)
        cell.todaysExerciseWeightLabel.text = finalKgWeight
        print(formatter.string(fromValue: kgWeight.value, unit: .kilogram))
    } else {
        let kgWeight = exerciseWeight.converted(to: .pounds)
        let finalLbWeight = formatter.string(fromValue: exerciseWeight.value, unit: .pound)
        cell.todaysExerciseWeightLabel.text = finalLbWeight
        print(formatter.string(fromValue: exerciseWeight.value, unit: .pound))
    }
}

}

jwarris91
  • 902
  • 9
  • 24

1 Answers1

5

It all boils down to the following piece of code:

let weight = Measurement(value: 10.0, unit: UnitMass.kilograms)

let formatter = MeasurementFormatter()
formatter.locale = Locale(identifier: "en_GB")

print(formatter.string(from: weight))

The result is an empty String (""). This is an obvious bug. Please, report it.

A simple workaround is using the older MassFormatter:

//let locale = Locale(identifier: "en_GB")
let locale = Locale(identifier: "en_US")

let weight = Measurement(value: 10.24, unit: UnitMass.pounds)

let formatter = MassFormatter()
formatter.numberFormatter.locale = locale
formatter.numberFormatter.maximumFractionDigits = 2

if locale.usesMetricSystem {
    let kgWeight = weight.converted(to: .kilograms)
    print(formatter.string(fromValue: kgWeight.value, unit: .kilogram))
} else {
    print(formatter.string(fromValue: weight.value, unit: .pound))
}
Sulthan
  • 128,090
  • 22
  • 218
  • 270
  • sorry to be a noob but how do i report things? Does this mean i cant finish this part of my app now? It seems odd that it works with en_US but not en_GB – jwarris91 Feb 09 '17 at 17:43
  • The string although it doesnt print, loads a value when using en_US, just not with en_GB, they both print empty but one still works... – jwarris91 Feb 09 '17 at 17:48
  • Thanks for adding the mass formatter code, im having some issues with it saying that 'Unit' is not a subtype of 'Dimensions' on the let kgWeight lines. What has i got wrong here? Added code to the OP. I presume i need to edit my exercise.weight objects when they save now to conform to a mass rather than measurement setup? – jwarris91 Feb 10 '17 at 11:46
  • @jwarris91 Replace `as! Measurement` with `as! Measurement`. – Sulthan Feb 10 '17 at 11:55
  • Thanks that seems to be working now, i reported the massformatter bug too – jwarris91 Feb 10 '17 at 12:12
  • 1
    An additional query if you have time, is there a way to prevent the 'kg' loading alongside the number? for example here... let finalKgWeight = formatter.string(fromValue: kgWeight.value, unit: .kilogram) and then setting userExerciseWeight.text = finalKgWeight will show "150 kg" in the text box, however my exercise builder only accepts integers so the 'kg' part crashes the app, i want it to just load the 150 part – jwarris91 Feb 10 '17 at 12:50
  • @jwarris91 If you don't want the units displayed, then use a simple `NumberFormatter` and not a `MassFormatter`... – Sulthan Feb 10 '17 at 12:56
  • thanks ill give it a go, its just in 1 instance where the user edits the object, its loading the units in after the number which causes a crash when its looking for an Integer, the Massformatter is fine in all other circumstances when its displaying uneditable data – jwarris91 Feb 10 '17 at 13:00
  • 1
    In theory i still need the mass formatter? as I may need to convert the metric between lb or kg, just only display the numbers? – jwarris91 Feb 10 '17 at 13:04