ios - presentLocalNotificationNow 和 scheduleLocalNotification 的区别

Question

presentLocalNotificationNow 和 scheduleLocalNotification 有什么区别。

因为以下两个函数都是在 1 秒后显示通知

-(void)showLocalNotification:(NSNotification *)notification {

    NSString *msg = @"test message";

    [[UIApplication sharedApplication] cancelAllLocalNotifications];

    UILocalNotification *_localNotification = [[UILocalNotification alloc]init];

    _localNotification.fireDate = [NSDate dateWithTimeIntervalSinceNow:1];

    _localNotification.timeZone = [NSTimeZone defaultTimeZone];

    _localNotification.alertBody = msg;

    _localNotification.soundName = UILocalNotificationDefaultSoundName;

    _localNotification.applicationIconBadgeNumber = [[UIApplication sharedApplication] applicationIconBadgeNumber]+1;

    [[UIApplication sharedApplication] scheduleLocalNotification:_localNotification];

    // or 

    //[[UIApplication sharedApplication] presentLocalNotificationNow:_localNotification];
}

Answer 1

如果应用程序在后台运行，本地通知将不会发出警报或声音，因为它直接由应用程序接收。在这种情况下，您需要使用 presentLocalNotificationNow 显示通知。

- (void)application:(UIApplication *)application didReceiveLocalNotification:(UILocalNotification *)notification
{
    UIApplicationState applicationState = application.applicationState;
    if (applicationState == UIApplicationStateBackground) {
        [application presentLocalNotificationNow:notification];
    }
}

来自 Apple 文档:

Once you have created an instance of UILocalNotification, you schedule it using one of two methods of the UIApplication class: scheduleLocalNotification: or presentLocalNotificationNow:. The former method use the fire date to schedule delivery; the latter method presents the notification immediately, regardless of the value of fireDate. You can cancel specific or all local notifications by calling cancelLocalNotification: or cancelAllLocalNotifications, respectively.