fatal error: Index out of range without using any array

Question

致命错误：当我使用循环

将日期转换为工作日时，没有使用任何数组，索引超出范围

 func getDayOfWeek(_ today:String) -> String? {
        let dateFormatter = DateFormatter()
        dateFormatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ssZ"
        let date = dateFormatter.date(from:today)
        let weekDay = dateFormatter.weekdaySymbols[Calendar.current.component(.weekday, from:date!)]
        return weekDay
    }

Answer 1

这是一个数组：

dateFormatter.weekdaySymbols

如果字符串格式错误，'date' 也可能为 nil。你应该这样检查：

func getDayOfWeek(_ today:String) -> String? {
    let dateFormatter = DateFormatter()
    dateFormatter.dateFormat = "yyyy-MM-dd"
    if let date = dateFormatter.date(from:today) {
        let weekDay = dateFormatter.weekdaySymbols[Calendar.current.component(.weekday, from:date)]
        return weekDay
    }
    return nil
}

Answer 2

Calendar.current.component(.weekday, from:date!) 从 1 到 7，但是 weekdaySymbols 的索引只能从 0 到 6，所以你必须减一才能得到正确的工作日：

let weekDay = dateFormatter.weekdaySymbols[Calendar.current.component(.weekday, from:date!)-1]

也应该使用 if let 并且像其他答案建议的那样是可选的，以避免崩溃

Answer 3

您可能需要将工作日转换为周索引！

let weekname = getWeekDayName(weekDay: calendar.component(.weekday, from: date()))

func getWeekDayName(weekDay:Int) -> String
{
    let f = DateFormatter()
    let index:Int = (weekDay - 1) % 7
    print("Week No: " + String(weekNo) + " No: " + String(index))
    let weekName = f.weekdaySymbols[index]
    print("Week Name: " + weekName)
    return weekName
}

fatal error: Index out of range without using any array

fatal error: Index out of range without using any array

nsdateformatter

ios