如果应用程序在前台运行，iOS不会显示通知横幅/警报。这是故意的。但我们可以通过使用UILocalNotification实现它，如下所示

Check whether application is in active state on receiving a remote notification. If in active state fire a UILocalNotification. if (application.applicationState == UIApplicationStateActive ) { UILocalNotification *localNotification = [[UILocalNotification alloc] init]; localNotification.userInfo = userInfo; localNotification.soundName = UILocalNotificationDefaultSoundName; localNotification.alertBody = message; localNotification.fireDate = [NSDate date]; [[UIApplication sharedApplication] scheduleLocalNotification:localNotification]; }

迅速:

if application.applicationState == .active {
    var localNotification = UILocalNotification()
    localNotification.userInfo = userInfo
    localNotification.soundName = UILocalNotificationDefaultSoundName
    localNotification.alertBody = message
    localNotification.fireDate = Date()
    UIApplication.shared.scheduleLocalNotification(localNotification)
}

您可以创建自己的通知，模仿横幅警报。

一种方法是创建一个自定义的uiview，看起来像横幅，可以动画和响应触摸。考虑到这一点，你可以创建更好的横幅，甚至更多的功能。

或者你可以寻找一个api来帮你做这件事，并把它们作为podfile添加到你的项目中。

以下是我使用过的一些方法:

https://github.com/terryworona/TWMessageBarManager

https://github.com/toursprung/TSMessages

对于任何可能感兴趣的人来说，我最终创建了一个自定义视图，看起来像顶部的系统推送横幅，但添加了一个关闭按钮(小蓝色X)和一个点击消息进行自定义操作的选项。它还支持在用户有时间阅读/删除旧通知之前到达多个通知的情况(没有限制可以堆积多少…)

链接到GitHub: AGPushNote

用法基本上是在线的:

[AGPushNoteView showWithNotificationMessage:@"John Doe sent you a message!"];

在iOS7上看起来是这样的(iOS6有一个iOS6的外观和感觉…)

Xcode 10 Swift 4.2

当你的应用程序在前台时，显示推送通知

步骤1:在AppDelegate类中添加delegate UNUserNotificationCenterDelegate。

class AppDelegate: UIResponder, UIApplicationDelegate, UNUserNotificationCenterDelegate {

步骤2:设置UNUserNotificationCenter委托

let notificationCenter = UNUserNotificationCenter.current()
notificationCenter.delegate = self

第三步:这一步将允许你的应用程序显示推送通知，即使你的应用程序在前台

func userNotificationCenter(_ center: UNUserNotificationCenter,
                                willPresent notification: UNNotification,
                                withCompletionHandler completionHandler: @escaping (UNNotificationPresentationOptions) -> Void) {
        completionHandler([.alert, .sound])

    }

步骤4:该步骤是可选的。检查你的应用程序是否在前台，如果在前台，然后显示本地推送通知。

func application(_ application: UIApplication,didReceiveRemoteNotification userInfo: [AnyHashable: Any],fetchCompletionHandler completionHandler:@escaping (UIBackgroundFetchResult) -> Void) {

        let state : UIApplicationState = application.applicationState
        if (state == .inactive || state == .background) {
            // go to screen relevant to Notification content
            print("background")
        } else {
            // App is in UIApplicationStateActive (running in foreground)
            print("foreground")
            showLocalNotification()
        }
    }

本地通知功能-

fileprivate func showLocalNotification() {

        //creating the notification content
        let content = UNMutableNotificationContent()

        //adding title, subtitle, body and badge
        content.title = "App Update"
        //content.subtitle = "local notification"
        content.body = "New version of app update is available."
        //content.badge = 1
        content.sound = UNNotificationSound.default()

        //getting the notification trigger
        //it will be called after 5 seconds
        let trigger = UNTimeIntervalNotificationTrigger(timeInterval: 1, repeats: false)

        //getting the notification request
        let request = UNNotificationRequest(identifier: "SimplifiedIOSNotification", content: content, trigger: trigger)

        //adding the notification to notification center
        notificationCenter.add(request, withCompletionHandler: nil)
    }

如果你的应用程序处于前台状态，这意味着你正在使用同一个应用程序。所以通常没有必要在顶部显示通知。

但如果你想显示通知在那种情况下你必须创建你的自定义警报视图或自定义视图像Toast或其他东西来向用户显示你已经收到通知。

如果你的应用中有这样的功能，你也可以在顶部显示一个徽章。

Objective - C

对于iOS 10，我们需要集成willPresentNotification方法来在前台显示通知横幅。

如果应用程序处于前台模式(活动)

- (void)userNotificationCenter:(UNUserNotificationCenter* )center willPresentNotification:(UNNotification* )notification withCompletionHandler:(void (^)(UNNotificationPresentationOptions options))completionHandler {
    NSLog( @"Here handle push notification in foreground" ); 
    //For notification Banner - when app in foreground
    
    completionHandler(UNNotificationPresentationOptionAlert);
    
    // Print Notification info
    NSLog(@"Userinfo %@",notification.request.content.userInfo);
}