我正在使用錯誤的文檔構造dateFormat來分析預定義格式的時間。 maddy(下)提供了正確文檔的鏈接。正確構建dateFormat在Swift 3.1中使用DateFormatter解析時間
這裏的時候我使用了錯誤的格式發生了什麼:
var idf = DateFormatter()
idf.locale = Locale(identifier: "en_US")
idf.dateStyle = .none
idf.dateFormat = "hh:MM:SSa"
// Of the variables defined here, the only one that doesn't cause an error
// is the last one:
var sMidnight: String = "12:00:00AM"
var sEarly: String = "12:40:22AM"
var sMorning: String = "6:00:00AM"
var sNoon: String = "12:00:00PM"
var sAfternoon: String = "12:30:22PM"
var sEvening: String = "7:05:45PM"
// Put any of the variables besides sEvening here and you get a crash.
// "fatal error: unexpectedly found nil while unwrapping an Optional value"
var date: Date = idf.date(from: sEvening)!
print(idf.string(from: date)) // prints 07:05:45 PM
請參閱關於格式說明符的文檔。你正在使用錯誤的。 – rmaddy