图表没有用二维数组绘制

Question

我有一个剑道图表，给出了如下所示的二维数组：

let price = 0 as NSDecimalNumber
let availableIdentifiers = Locale.availableIdentifiers
var allCurrencySymbols: String = ""
for identifier in availableIdentifiers
{
    let locale = Locale(identifier: identifier)
    let formatter = NumberFormatter()
    formatter.formatterBehavior = NumberFormatter.Behavior.behavior10_4
    formatter.numberStyle = NumberFormatter.Style.currency
    formatter.locale = locale

    let formattedPrice = formatter.string(from: price)!
    let currencySymbolsOnly = formattedPrice.replacingOccurrences(of: "0", with: "")
    allCurrencySymbols.append(currencySymbolsOnly)
}

var set = Set<Character>()
let allCurrencySymbolsMinusDuplicates = String(allCurrencySymbols.characters.filter{ set.insert($0).inserted } )
print(allCurrencySymbolsMinusDuplicates)

但我在图表上看不到任何内容。我的图表是：

[['a'],[2]],[['b'],[3]]]