即使当前未在设备上打开应用，如何向用户提供本地用户通知

Question

我正在尝试根据日期列表向用户提供通知。当其中一个日期与当前日期匹配时，我希望用户收到通知。如果应用程序已经在运行，那么我当前拥有的代码效果很好。但是，如果用户关闭应用程序，则不再提供通知。

下面是我已经尝试过的代码：

func userNotification() {
    let content = UNMutableNotificationContent()
    let allDiscounts = discountBank()
    let dateClass = theDate()
    var my1 = 0
    var myList = [Int]()

    for i in 0...allDiscounts.list.count-1 {
        if dateClass.todaysDate > allDiscounts.list[i].dateApplied {
            my1 = i+1
        }
    }
    myList.append(my1)
    for i in my1+1...allDiscounts.list.count-1{
        myList.append(i)
    }
    if my1>=1{
        for i in 0...my1-1{
            myList.append(i)
        }
    }
    print(myList)
    content.title = "Todays Deal at \(allDiscounts.list[myList[0]].businessName)"
    content.body = allDiscounts.list[myList[0]].theDeal
    content.sound = UNNotificationSound.default
    let components = DateComponents(month:theDate().month, day:theDate().day, hour:11, minute:28)

    if theDate().todaysDate == allDiscounts.list[myList[0]].dateApplied {

        let trigger = UNCalendarNotificationTrigger(dateMatching: components, repeats: false)
        let request = UNNotificationRequest(identifier: "TestIdentifier", content: content, trigger: trigger)
        UNUserNotificationCenter.current().add(request, withCompletionHandler: nil)

    }
}