Why does UIUserNotificationType.None return true in the current settings when user permission is given?

问题

I'm writing a method to check if the current user settings consist of certain notification types.

When checking whether the current settings contain UIUserNotificationsType.None, it returns true for both when the permission was given and denied. Would anyone know why this is?

func registerForAllNotificationTypes()
{
    registerNotificationsForTypes([.Badge, .Alert, .Sound])
}

func registerNotificationsForTypes(types:UIUserNotificationType)
{
    let settings = UIUserNotificationSettings.init(forTypes:types, categories: nil)
    UIApplication.sharedApplication().registerUserNotificationSettings(settings)
}

func isRegisteredForAnyNotifications() -> Bool
{
    let currentSettings = UIApplication.sharedApplication().currentUserNotificationSettings()
    print(currentSettings)
    print((currentSettings?.types.contains(.Alert))!)
    print((currentSettings?.types.contains(.Badge))!)
    print((currentSettings?.types.contains(.Sound))!)
    print((currentSettings?.types.contains(.None))!)

    return (currentSettings?.types.contains(.Alert))! //Just testing .Alert for now
}

When permission is on:

Optional(<UIUserNotificationSettings: 0x7fabdb719360; types: (UIUserNotificationTypeAlert UIUserNotificationTypeBadge UIUserNotificationTypeSound);>) true true true true

When permission is off:

Optional(<UIUserNotificationSettings: 0x7f96d9f52140; types: (none);>) false false false true

回答1:

Funny thing, it just confirms that 0 contains 0 :) Take a look on enum definition for UIUserNotificationsType: https://developer.apple.com/library/prerelease/ios/documentation/UIKit/Reference/UIUserNotificationSettings_class/index.html#//apple_ref/c/tdef/UIUserNotificationType

struct UIUserNotificationType : OptionSetType {
    init(rawValue rawValue: UInt)
    static var None: UIUserNotificationType { get }
    static var Badge: UIUserNotificationType { get }
    static var Sound: UIUserNotificationType { get }
    static var Alert: UIUserNotificationType { get }
}

But it's more clearly visible in Objective-C:

typedef enum UIUserNotificationType : NSUInteger {
   UIUserNotificationTypeNone    = 0,
   UIUserNotificationTypeBadge   = 1 << 0,
   UIUserNotificationTypeSound   = 1 << 1,
   UIUserNotificationTypeAlert   = 1 << 2,
} UIUserNotificationType;

来源：https://stackoverflow.com/questions/32248411/why-does-uiusernotificationtype-none-return-true-in-the-current-settings-when-us

标签

ios

swift2