我正在嘗試將我的 AM PM 時間選擇器轉換為 24 小時格式以列印開始和結束時間以計算價格，但出現未知錯誤。附件是我的 UI 的照片，以簡化想法和我的代碼。注意：選擇開始時間后會自動顯示結束時間
@objc func donePressed(){
// formatter
let formatter = DateFormatter()
formatter.dateStyle = .none
formatter.timeStyle = .short
startTimeTxt.text = formatter.string(from: StartTimePicker.date)
self.view.endEditing(true)
endTimeTxt.text = formatter.string(from: EndTimePicker.date)
self.view.endEditing(true)
let starttimecal = StartTimeTxt.text!
let endtimecal = EndTimeTxt.text!
let StartTo24 = starttimecal
let EndTo24 = endtimecal
let dateFormatter = DateFormatter()
dateFormatter.dateFormat = "h:mm a"
let sTime = dateFormatter.date(from: startTo24)
dateFormatter.dateFormat = "HH:mm"
let sTime24 = dateFormatter.string(from: sTime!)
print("24 hour formatted Date:", sTime24)
let eTime = dateFormatter.date(from: endTo24)
dateFormatter.dateFormat = "HH:mm"
let eTime24 = dateFormatter.string(from: eTime!) // here the fatal error comes after i choose the start time from simulator
print("24 hour formatted Date:", eTime24)
}
uj5u.com熱心網友回復：
要在文本欄位中顯示 12 小時時間格式，您可以使用已有的格式化程式，但我也喜歡設定語言環境
let dateFormatter12h = DateFormatter()
dateFormatter12h.locale = Locale(identifier: "en_US_POSIX")
dateFormatter12h.dateFormat = "h:mm a"
為了計算時差，在Calendar課堂上有一個函式，這里我們計算兩個日期之間的小時數和分鐘數（這是一個假設，因為我不知道你想要做什么計算）
let hourAndMinutes = Calendar.current.dateComponents([.hour, .minute], from: startDate, to: endDate)
下面是一個更完整的例子
//Sample data
let startDate = Date()
let endDate = startDate.addingTimeInterval(3.25*60*60) //add 3h and 15 minutes
// Format and print in 12h format
let dateFormatter12h = DateFormatter()
dateFormatter12h.locale = Locale(identifier: "en_US_POSIX")
dateFormatter12h.dateFormat = "h:mm a"
let start = dateFormatter12h.string(from: startDate)
let end = dateFormatter12h.string(from: endDate)
print(start, end)
// Calculate time difference in hours and minutes
let hourAndMinutes = Calendar.current.dateComponents([.hour, .minute], from: startDate, to: endDate)
print(hourAndMinutes)
// Calculate price, the formula is just an example
let price = hourAndMinutes.hour! * 15 hourAndMinutes.minute! * 15 / 60
print(price)
輸出
下午 6:46 晚上 10:01
小時：3 分鐘：15 isLeapMonth：假
48
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