如何从标准datetime格式中提取日期和时间？

用于DateFormatter从中获取Date实例String，即

let str = "2019-08-12T10:34:05.000Z"
let formatter = DateFormatter()
formatter.locale = Locale(identifier: "en_US_POSIX")
formatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ss.SSSZ"
let date = formatter.date(from: str)

现在，要获取时差，请使用timeIntervalSince(_:)2个Date对象，即

let startedOn = "2019-08-12T10:32:18.000Z"
let stoppedOn = "2019-08-12T10:34:05.000Z"
if let startedOnDate = formatter.date(from: startedOn), let stoppedOnDate = formatter.date(from: stoppedOn) {
    let timeInterval = stoppedOnDate.timeIntervalSince(startedOnDate)
    print(timeInterval)
}

如果您需要2个Date对象之间更详细的组件，请Calendar像这样使用对象，

if let startedOnDate = formatter.date(from: startedOn), let stoppedOnDate = formatter.date(from: stoppedOn) {
    let calendar = Calendar(identifier: .gregorian)
    let components = calendar.dateComponents([.hour, .minute, .second], from: startedOnDate, to: stoppedOnDate)
    print(components) //hour: 0 minute: 1 second: 47
}

编辑：

要获取date和time与Date对象分开，

let str = "2019-08-12T10:34:05.000Z"
let formatter = DateFormatter()
formatter.locale = Locale(identifier: "en_US_POSIX")
formatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ss.SSSZ"
if let date = formatter.date(from: str) {
    formatter.dateFormat = "hh:mm:ss a"
    let timeStr = formatter.string(from: date)
    print(timeStr) //add timeStr to your timeLabel here...

    formatter.dateFormat = "yyyy-MM-dd"
    let dateStr = formatter.string(from: date)
    print(dateStr) //add dateStr to your dateLabel here...
}