迅捷3-无法将字符串转换为日期 [英] swift 3 - can not convert string to date

问题描述

无论我做什么，我都无法将RSSs pubDate(当然是字符串)转换为 Date .

No matter what I do, I can not convert an RSSs pubDate (which is a string of course) into a Date.

以下是日期字符串: Sun，2017年4月2日19:31:18 GMT

这是我的代码:

private var dateBuffer: Date {
    formatter.dateFormat = "EEE, dd MMM yyyy hh:mm:ss zzz"
    let date = formatter.date(from: buffers["pubDate"]!) //<-date comes back nil
    return date! //<-program crashes
}

date 始终返回 nil .可能是什么问题?

date always returns nil. What maybe the problem??

推荐答案

如果您非常确定 buffers ["pubDate"]！等于"Sun，2017年4月2日19:31:18 GMT"(或任何具有相同格式的日期)，则应为:

If your are pretty sure that buffers["pubDate"]! is equal to "Sun, 02 Apr 2017 19:31:18 GMT" (or any date with the same format), then it should be:

var dateBuffer: Date {
    let formatter = DateFormatter()
    formatter.dateFormat = "EEE, dd MMM yyyy HH:mm:ss zzz"
    let date = formatter.date(from: buffers["pubDate"]!)
    return date!
}

请注意，区别是 HH:mm:ss 而不是 hh:mm:ss .要将小时读为24时制惯例，应使用 HH .

Note that the difference is HH:mm:ss instead of hh:mm:ss. For reading the hours as 24-clock convention, you should use HH.

为了更加安全-避免任何意外崩溃-我建议做一些可选绑定，如下所示:

Also, to be more safe -from any unexpected crash-, I'd suggest to do some optional binding, as follows:

var dateBuffer: Date? {
    let formatter = DateFormatter()
    let str:String? = "Sun, 02 Apr 2017 19:31:18 GMT"

    formatter.dateFormat = "EEE, dd MMM yyyy HH:mm:ss zzz"
    if let pubDate = buffers["pubDate"], let date = formatter.date(from: pubDate) {
        return date
    }

    return nil
}

if let myDate = dateBuffer {
    print(myDate)
}

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