能否通过编程方式重新唤起iOS推送通知提醒（用户已选“Don't Allow”后）

Short answer: No, you can't trigger the original system-provided push permission alert programmatically once the user has declined it.

Here's why: Apple's permission framework is built to prevent developers from spamming users with repeated permission requests. Once a user explicitly taps "Don't Allow" for push notifications, any subsequent calls to UNUserNotificationCenter.requestAuthorization() won't display the system prompt—they'll immediately return a denied status in the completion handler instead.

What You Can Do Instead #

Create a custom, user-centric alert that clearly explains why you need push permissions (e.g., "We’ll send you order updates and exclusive event reminders"), then provide a direct shortcut to your app's settings page where users can manually enable notifications.

Here's a practical Swift implementation:

1. Check Current Permission Status First

import UserNotifications

func checkPushPermissionStatus() {
    UNUserNotificationCenter.current().getNotificationSettings { [weak self] settings in
        DispatchQueue.main.async {
            switch settings.authorizationStatus {
            case .notDetermined:
                // User hasn't been asked yet—trigger the original system prompt
                self?.requestOriginalPushPermission()
            case .denied:
                // User declined before—show custom guidance alert
                self?.showPermissionExplanationAlert()
            case .authorized, .provisional, .ephemeral:
                // Permissions already granted—proceed with setup
                self?.setupPushNotifications()
            @unknown default:
                break
            }
        }
    }
}

2. Request Original Permission (For First-Time Users)

func requestOriginalPushPermission() {
    UNUserNotificationCenter.current().requestAuthorization(options: [.alert, .badge, .sound]) { granted, error in
        DispatchQueue.main.async {
            if granted {
                self.setupPushNotifications()
            }
            // If denied, the next check will trigger the custom alert
        }
    }
}

3. Show Custom Explanation Alert

func showPermissionExplanationAlert() {
    let alert = UIAlertController(
        title: "Enable Push Notifications",
        message: "Push notifications keep you in the loop with important updates like order confirmations, flash sales, and appointment reminders. To turn them on, head to your app settings.",
        preferredStyle: .alert
    )
    
    alert.addAction(UIAlertAction(title: "Cancel", style: .cancel))
    alert.addAction(UIAlertAction(title: "Go to Settings", style: .default) { _ in
        // Directly open the app's settings page
        guard let settingsURL = URL(string: UIApplication.openSettingsURLString) else { return }
        if UIApplication.shared.canOpenURL(settingsURL) {
            UIApplication.shared.open(settingsURL)
        }
    })
    
    present(alert, animated: true)
}

4. Helper to Set Up Push Notifications (Once Granted)

func setupPushNotifications() {
    // Register for remote notifications and configure notification categories
    UIApplication.shared.registerForRemoteNotifications()
}

This approach follows Apple's guidelines while still guiding users to enable permissions when needed—plus, explaining the value of push notifications can drastically improve the chance users will enable them in settings.

内容的提问来源于stack exchange，提问作者Madhavan