无法从源自JSON的字符串格式化货币

Question

我想从字符串格式化货币：

let formatter = NumberFormatter()
formatter.numberStyle = .currency
formatter.numberStyle = .currency
formatter.locale = Locale(identifier: "en_US")
thetotal_balancestring = "$456.78"
let number = formatter.number(from: thetotal_balancestring)

工作正常。 但是如果我使用的是一个我从JSON获得的字符串，那么我无法正确使用它，尽管它显然是一个字符串。

if (object["total_balance"] == nil) {
thetotal_balance = 0
} else {
thetotal_balancestring = (object["total_balance"] as! String)

let formatter = NumberFormatter()
formatter.numberStyle = .currency
formatter.locale = Locale(identifier: "en_US")

if let number = formatter.number(from: thetotal_balancestring) {
let amount = number.decimalValue
print(amount)
} else {
print ("could not succeed despite string seems valid:  \(thetotal_balancestring)")
}

打印：尽管字符串似乎有效，但无法成功：5,724.12

Answer 1

确保其前缀为$：

let formatter = NumberFormatter()
formatter.numberStyle = .currency
formatter.locale = Locale(identifier: "en_US")
let thetotal_balancestring = "$5,724.12"
let number = formatter.number(from: thetotal_balancestring)

结果：5724.12