Swift把iso8601字符串日期格式转换成Date格式

当项目为 Swift 4 • iOS 11 或更高的版本用一下写法

extension Formatter {
    static let iso8601: ISO8601DateFormatter = {
        let formatter = ISO8601DateFormatter()
        formatter.formatOptions = [.withInternetDateTime, .withFractionalSeconds]
        return formatter
    }()
}

使用方法

let dateString = Formatter.iso8601.string(from: Date())   // "2018-01-23T03:06:46.232Z"
if let date = Formatter.iso8601.date(from: dateString)  {
    print(date)   // "2018-01-23 03:06:46 +0000\n"
}

当项目为 Swift 3.0.2 或 iOS 11 以下的版本，用下面的写法

extension Formatter {
    static let iso8601: DateFormatter = {
        let formatter = DateFormatter()
        formatter.calendar = Calendar(identifier: .iso8601)
        formatter.locale = Locale(identifier: "en_US_POSIX")
        formatter.timeZone = TimeZone(secondsFromGMT: 0)
        formatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ss.SSSXXXXX"
        return formatter
    }()
}
extension Date {
    var iso8601: String {
        return Formatter.iso8601.string(from: self)
    }
}

extension String {
    var dateFromISO8601: Date? {
        return Formatter.iso8601.date(from: self)   // "Mar 22, 2017, 10:22 AM"
    }
}

使用方法

let stringFromDate = Date().iso8601    // "2017-03-22T13:22:13.933Z"

if let dateFromString = stringFromDate.dateFromISO8601 {
    print(dateFromString.iso8601)      // "2017-03-22T13:22:13.933Z"
}