iPhone 24 小时日期格式中的日期转换始终为零

Question

我正在尝试将字符串转换为以 12 小时制日期格式正常工作的日期。当我将设备日期格式切换为 24 时，它总是返回 nil。请检查以下代码

    let formatter = DateFormatter()
    formatter.dateFormat = "h:mm a"
    let date = formatter.date(from: "6:00 am")

Answer 1

根据Technical Q&A QA1480：

if you're working with fixed-format dates, you should first set the locale of the date formatter to something appropriate for your fixed format. In most cases the best locale to choose is "en_US_POSIX", a locale that's specifically designed to yield US English results regardless of both user and system preferences.

因此，要防止使用设备的区域设置解释日期，您需要设置 DateFormatter

的 locale 属性

let formatter = DateFormatter()
formatter.locale = Locale(identifier: "en_US_POSIX")
formatter.dateFormat = "hh:mm a"
let date = formatter.date(from: "6:00 am")

注意：在设置 dateFormat

之前设置 locale 很重要

iPhone 24 小时日期格式中的日期转换始终为零

Date conversion is always nil in iPhone 24hr date format

xcode

nsdateformatter

ios

swift3