UILocalNotification 安排警报

Question

我安排了一个通知，并在它显示警报消息之前给它 60 分钟警告...

添加通知后，我的应用程序委托中的方法就会被调用：

- (void)application:(UIApplication *)application didReceiveLocalNotification:(UILocalNotification *)notification

我怎样才能知道它将在后台显示为警报？我是否需要重写或使用任何其他委托方法，以确保给定间隔为 60 分钟的预定警报...

- (void)scheduleNotificationWithItem:(NSDate *)item interval:(int)minutesBefore
{   
    NSCalendar *calendar = [NSCalendar autoupdatingCurrentCalendar];

    NSDateComponents *dateComps = [[NSDateComponents alloc] init];
    //NSCalendar *gregorian = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];

    NSDateComponents *currentDateComponents = [calendar components:( NSWeekdayCalendarUnit | 
                                                                     NSYearCalendarUnit | NSMonthCalendarUnit | NSHourCalendarUnit | NSMinuteCalendarUnit | NSWeekCalendarUnit | NSMinuteCalendarUnit) fromDate:item];

    NSLog(@"- current components year = %i , month = %i , week = % i, weekday = %i", [currentDateComponents year], [currentDateComponents month], [currentDateComponents week], [currentDateComponents weekday]);

    NSLog(@"[currentDateComponents minute]: %i",    [currentDateComponents minute]);
    NSLog(@"[currentDateComponents hour]: %i",      [currentDateComponents hour]);
    NSLog(@"[currentDateComponents day]: %i",       [currentDateComponents day]);
    NSLog(@"[currentDateComponents week]: %i",      [currentDateComponents week]);
    NSLog(@"[currentDateComponents month]: %i",     [currentDateComponents month]);
    NSLog(@"[currentDateComponents year]: %i",      [currentDateComponents year]);

    [dateComps setDay: [currentDateComponents day]];

    [dateComps setMonth:[currentDateComponents month]];

    [dateComps setYear:[currentDateComponents year]];

    [dateComps setHour:[currentDateComponents hour]];

    [dateComps setMinute:[currentDateComponents minute]];

    NSDate *itemDate = [calendar dateFromComponents:dateComps];

    [dateComps release];

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

    if (localNotif == nil)
        return;

    localNotif.fireDate = [itemDate addTimeInterval:-(minutesBefore*60)];

    localNotif.timeZone = [NSTimeZone defaultTimeZone];

    localNotif.alertBody = [NSString stringWithFormat:@"%@\n%@",
                            streetAddress,
                            stringOfWhenAuctionIsOn];

    localNotif.alertAction = NSLocalizedString(@"View Details", nil);

    localNotif.soundName = UILocalNotificationDefaultSoundName;

    localNotif.applicationIconBadgeNumber = 1;

    NSDictionary *infoDict = [NSDictionary dictionaryWithObject:streetAddress
                                                         forKey:idOfStreetAlert];

    localNotif.userInfo = infoDict;

    [[UIApplication sharedApplication] scheduleLocalNotification:localNotif];

Answer 1

如果立即显示通知，则您的 fireDate 属性可能有问题。看起来您正在尝试验证发送的日期是否正确，但您还应该验证 fireDate 是否是您所期望的。

另外，您也许可以

localNotif.fireDate = [item dateByAddingTimeInterval:-60*minutesBefore];

实现相同的效果，而不必使用 NSDateComponents。我还没有测试过这个，但它可能会起作用。

至于当计时器触发并且您的应用程序未运行时会发生什么。如果应用程序尚未终止，application:didReceiveLocalNotification: 将被调用。如果您的应用程序已被终止，您需要检查 application:didFinishLaunchingWithOptions: 正如 @Ishu 所指出的。我通常只是将通知传递给通用方法以避免重复代码。

Answer 2

后台没有委托方法，您需要在 didFinishLaunchingWithOptions 中编写代码，

UILocalNotification *localNotif =
    [launchOptions objectForKey:UIApplicationLaunchOptionsLocalNotificationKey];

    if (localNotif) {
        //your code
        NSLog(@"Recieved Notification %@",localNotif);
    }

当应用程序从后台获取通知时，它会创建您的逻辑。不用担心应用程序会收到您设置通知的通知。