Ios Switch语句而不是大量if语句

我目前正在处理通知，希望打印出一个标识符。如何用一个开关替换所有if语句

以下是我的枚举，它将所有标识符与相应的字符串值保持一致：

    enum NotificationIdentifier:String {
    case local = "Local Notification"
    case localWithAction = "Local Notification with Action"
    case localWithContent = "Local Notification with Content"
    case pushWithAPNs = "Push Notification with  APNs"
    case pushWithFirebase = "Push Notification with Firebase"
    case pushWithContent = "Push Notification with Content"
}

和我的委托方法：

func userNotificationCenter(_ center: UNUserNotificationCenter, didReceive response: UNNotificationResponse, withCompletionHandler completionHandler: @escaping () -> Void) {

    if response.notification.request.identifier == NotificationIdentifier.local.rawValue {
        print("Handling notification with the \(NotificationIdentifier.local.rawValue)")
    } else if response.notification.request.identifier == NotificationIdentifier.localWithAction.rawValue {
        print("Handling notification with the \(NotificationIdentifier.localWithAction.rawValue)")
    } else if response.notification.request.identifier == NotificationIdentifier.localWithContent.rawValue {
        print("Handling notification with the \(NotificationIdentifier.localWithContent.rawValue)")
    } else if response.notification.request.identifier == NotificationIdentifier.pushWithAPNs.rawValue {
        print("Handling notification with the \(NotificationIdentifier.pushWithAPNs.rawValue)")
    } else if response.notification.request.identifier == NotificationIdentifier.pushWithFirebase.rawValue {
        print("Handling notification with the \(NotificationIdentifier.pushWithFirebase.rawValue)")
    } else {
        print("Handling notification with the \(NotificationIdentifier.pushWithContent.rawValue)")
    }

    completionHandler()
}

---

可以在枚举上使用如下开关大小写：

func userNotificationCenter(_ center: UNUserNotificationCenter, didReceive response: UNNotificationResponse, withCompletionHandler completionHandler: @escaping () -> Void) {
    switch response.notification.request.identifier {
        case .local:
            print("local")
        case .localWithAction:
            print("localWithAction")
        case .localWithAction:
            print("localWithAction")
        case .localWithContent:
            print("localWithContent")
        case .pushWithAPNs:
            print("pushWithAPNs")
        case .pushWithFirebase:
            print("pushWithFirebase")
    default:
        print("pushWithContent")
    }
    completionHandler()
}

---

您可以避免像这样的switch和if-else语句。。。这段代码将为您提供

NotificationIdentifier

case

func userNotificationCenter(_ center: UNUserNotificationCenter, didReceive response: UNNotificationResponse, withCompletionHandler completionHandler: @escaping () -> Void) {


    if let notificationIdentifier =   NotificationIdentifier(rawValue: response.notification.request.identifier) {

        print("Handling notification with the \(notificationIdentifier.rawValue)")

        switch notificationIdentifier {
        case .local:
            print("Handle local")
        case .localWithAction:
            print("Handle localWithAction")
        case .localWithContent:
            print("Handle localWithContent")
        case .pushWithAPNs:
            print("Handle pushWithAPNs")
        case .pushWithFirebase:
            print("Handle pushWithFirebase")
        case .pushWithContent:
            print("Handle pushWithContent")

        }


    } else {
        print("cant convert to NotificationIdentifier")
    }

    completionHandler()
}

如果只想打印出标识符，可以使用单个打印语句：

let notificationIdentifier = NotificationIdentifier.init(rawValue: response.notification.request.identifier) ?? .pushWithContent)
print("Handling notification with the \(notificationIdentifier.rawValue)")

---

这也将包括默认值（例如

.pushWithContent

）。

初始化

通知标识符的
枚举
，并使用如下开关情况：

func userNotificationCenter(_ center: UNUserNotificationCenter, didReceive response: UNNotificationResponse, withCompletionHandler completionHandler: @escaping () -> Void) {
    guard let notificationIdentifier = NotificationIdentifier(rawValue: response.notification.request.identifier) else { return }
    switch notificationIdentifier {
    case .local:
    print("Handling notification with the \(NotificationIdentifier.local.rawValue)")
    case .localWithAction:
    print("Handling notification with the \(NotificationIdentifier.localWithAction.rawValue)")
    case .localWithContent:
    print("Handling notification with the \(NotificationIdentifier.localWithContent.rawValue)")
    case .pushWithAPNs:
    print("Handling notification with the \(NotificationIdentifier.pushWithAPNs.rawValue)")
    case .pushWithFirebase:
    print("Handling notification with the \(NotificationIdentifier.pushWithFirebase.rawValue)")
    case .pushWithContent:
    print("Handling notification with the \(NotificationIdentifier.pushWithContent.rawValue)")
    }
}

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