如何知道推送通知权限警报是否已显示

Question

我想实现一个自定义屏幕，通知我的用户我为什么要请求推送通知权限。在他们按下该自定义屏幕中的按钮后，我会显示带有 [[UIApplication sharedApplication] registerForRemoteNotificationTypes: 的 iOS 推送通知权限对话框

如果用户尚未看到推送通知权限对话框，我只想显示此自定义屏幕一次。我不能使用[[UIApplication sharedApplication] enabledRemoteNotificationTypes] == UIRemoteNotificationTypeNone，因为如果用户决定不允许推送通知，这也会返回“无”。

有什么想法吗？

Answer 1

你可以使用 NSUserDefaults ：

#define kPushNotificationRequestAlreadySeen @"PushNotificationRequestAlreadySeen"

if(![[NSUserDefaults standardUserDefaults] boolForKey:kPushNotificationRequestAlreadySeen]) {

    // Notify the user why you want to have push notifications
    UIAlertView *alertView = [[UIAlertView alloc] initWithTitle:... delegate:self ...];
    [alertView show];

    [[NSUserDefaults standardUserDefaults] setBool:YES forKey:kPushNotificationRequestAlreadySeen];
}
else {
    // Already allowed -> register without notifying the user
    [[UIApplication sharedApplication] registerForRemoteNotificationTypes:UIRemoteNotificationTypeAlert | UIRemoteNotificationTypeBadge | UIRemoteNotificationTypeSound];
}

还有

- (void)alertView:(UIAlertView*)alertView didDismissWithButtonIndex:(NSInteger)index {
    // Actually registering to push notifications
    [[UIApplication sharedApplication] registerForRemoteNotificationTypes:UIRemoteNotificationTypeAlert | UIRemoteNotificationTypeBadge | UIRemoteNotificationTypeSound];
}

Answer 2

这只是一种变通方法，但在大多数情况下都可以使用。

当 iOS 提示用户允许推送通知时，会调用 applicationWillResignActive。

在调用 registerForRemoteNotificationTypes...启动一个计时器（或 dispatch_after），它将向用户显示一个新警报，说明他们需要使用“设置”应用来启用通知。然后在 applicationWillResignActive 中取消定时器。这样，解释警报只会在 applicationWillResignActive 从未被调用时显示。

我看到的唯一问题是，如果应用程序在计时器运行的确切时间因其他原因退出活动......但这不会让你处于更糟糕的情况下，你已经处于并且具有优势在大多数情况下工作。

Answer 3

我发现的解决方案有点破解，但它确实有效。 您需要调用registerUserNotificationSettings 来获取两种不同的通知设置——一种没有notificationCategory，另一种有notificationCategory：

        //Request notification permission
    UIUserNotificationSettings *notificationSettings = [UIUserNotificationSettings settingsForTypes:UIUserNotificationTypeAlert | UIUserNotificationTypeBadge | UIUserNotificationTypeSound categories:nil];
    [[UIApplication sharedApplication] registerUserNotificationSettings:notificationSettings];

    //Request notification permission again, but with a category with no actions
    UIMutableUserNotificationCategory *category = [[UIMutableUserNotificationCategory alloc] init];
    category.identifier = @"com.xyz.markNotificationPopupShownCategoryIdentifier";

    UIUserNotificationSettings *notificationSettingsWithCategory = [UIUserNotificationSettings settingsForTypes:UIUserNotificationTypeAlert | UIUserNotificationTypeBadge | UIUserNotificationTypeSound categories:[NSSet setWithObject:category]];
    [[UIApplication sharedApplication] registerUserNotificationSettings:notificationSettingsWithCategory];

appdelegate中的didRegisterUserNotificationSettings:(UIUserNotificationSettings *)notificationSettings方法会被调用两次，无论用户在权限通知中的回答如何，第二次调用后，当前通知设置都会包含该类别。只要类别计数大于0，就可以确定已经显示了通知权限对话框：

if ([UIApplication sharedApplication].currentUserNotificationSettings.categories.count > 0) {
    NSLog(@"Notifications permission has been asked");
} else {
    NSLog(@"Notifications permission hasn't been asked");
}