How to format a Double into Currency – Swift 3

You can use this string initializer if you want to force the currency to $:

String(format: "Tip Amount: $%.02f", tipAmount)

If you want it to be fully dependent on the locale settings of the device, you should use a NumberFormatter. This will take into account the number of decimal places for the currency as well as positioning the currency symbol correctly. E.g. the double value 2.4 will return “2,40 €” for the es_ES locale and “¥ 2” for the jp_JP locale.

let formatter = NumberFormatter()
formatter.locale = Locale.current // Change this to another locale if you want to force a specific locale, otherwise this is redundant as the current locale is the default already
formatter.numberStyle = .currency
if let formattedTipAmount = formatter.string(from: tipAmount as NSNumber) {
    tipAmountLabel.text = "Tip Amount: \(formattedTipAmount)"

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