ios - 找出最后触发的 UILocalNotification

Question

我正在开发一个使用 UILocalNotifications 的 iOS 闹钟应用。到目前为止一直很好，直到有人想出显示从用户所在位置到他想去的位置的路线的想法。

为此，我想我也许可以获得最后一次触发的 UILocalNotification(所有这些都将 repeatInterval 设置为每周或每天)。

这就是整个麻烦的来源，因为 fireDate 是我第一次安排它们:这是我的场景:

        UILocalNotification* ln = [[UILocalNotification alloc] init];
        ln.fireDate = date; // For instance 07/19/2014 10:00:00 (Saturday)
        ln.repeatInterval = NSDayCalendarUnit;            
        [[UIApplication sharedApplication] scheduleLocalNotification:ln];

        UILocalNotification* ln = [[UILocalNotification alloc] init];
        ln.fireDate = date; // For instance 07/17/2014 11:00:00 (Thursday)
        ln.repeatInterval = NSWeekCalendarUnit;            
        [[UIApplication sharedApplication] scheduleLocalNotification:ln];

想象一下:

下周四 (07/24/2014 11:00:01) 我想知道最后一个触发的 UILocalNotification 是第二个只在周四重复的，第二天我想要第一个，因为它每天重复。

我尝试按日期对所有 LocalNotifications 进行排序，但没有成功。

有没有人遇到过类似的情况？

问候

Answer 1

即使通过 repeatInterval 属性安排它自己重复，iOS 也会在触发后丢弃本地通知。

[UIApplication sharedApplication].scheduledLocalNotifications 实际上会返回计划在 future 触发的所有通知。 所以他们的fireDate将被设置为 future 的一个日期。

经过进一步调查，fireDate 似乎始终设置为创建通知时指定的原始值。然而，下一个开火日期，一个计算值，将在未来。要查看此值，只需在调试器中运行 po yourNotificationObj，您将看到以下类型的输出，其中包括下一个触发日期:

{fire date = Saturday, July 26, 2014 at 1:42:50 PM Eastern Daylight Time, time zone = (null), repeat interval = NSMinuteCalendarUnit, repeat count = UILocalNotificationInfiniteRepeatCount, next fire date = Saturday, July 26, 2014 at 1:43:50 PM Eastern Daylight Time, user info = (null)}

您如何计算下一个点火日期？请参阅以下摘自 How to grab the NEXT fire date from a UILocalNotification object 的代码:

NSCalendar *calendar = localNotif.repeatCalendar;
if (!calendar) {
  calendar = [NSCalendar currentCalendar];
}

NSDateComponents *components = [[[NSDateComponents alloc] init] autorelease];
// If you use some other repeat interval you would have to change the code accordingly. 
// If you were to use NSMonthCalendarUnit you would have 
// to use `components.month = 1' instead
components.day = 1;
NSDate *nextFireDate = [calendar dateByAddingComponents:components toDate:localnotif.fireDate options:0];

如果您想记住最后触发的本地通知，则必须将该逻辑构建到您的应用中并保存所需信息。例如，您可以执行以下操作:

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    UILocalNotification *localNotification = [launchOptions objectForKey:UIApplicationLaunchOptionsLocalNotificationKey];

    if (localNotification) {
        [self saveLocalNotification:localNotification];
    }

    return YES;
}

- (void)application:(UIApplication *)application didReceiveLocalNotification:(UILocalNotification *)notification
{
    [self saveLocalNotification:notification];
}

- (void)saveLocalNotification:(UILocalNotification *)notification
{
    // save information about the last fired local notification on disk
}

- (UILocalNotification *)lastFiredLocalNotification
{
    // read the information stored on disk by the saveLocalNotification: method
    // and recreate the notification. I'm just saying recreate the notification
    // because I don't know what exactly you're trying to do. You 
    // can return anything you want here
}

使用上述设置，您可以在需要时调用lastFiredLocalNotification 方法。