iOS本地通知:UILocalNotification
在去年做过一个小App,其中使用的关键功能就是向用户发送本地通知,可惜当时没有写博客的习惯,所以没有将对应的知识记录下来。最近又遇到了该功能的使用,这一次果断写个博客做下有关UILocalNotification的笔记。
首先是添加一个本地通知到系统中,代码如下:
// 初始化本地通知对象 UILocalNotification *notification = [[UILocalNotification alloc] init]; if (notification) { // 设置通知的提醒时间 NSDate *currentDate = [NSDate date]; notification.timeZone = [NSTimeZone defaultTimeZone]; // 使用本地时区 notification.fireDate = [currentDate dateByAddingTimeInterval:5.0]; // 设置重复间隔 notification.repeatInterval = kCFCalendarUnitDay; // 设置提醒的文字内容 notification.alertBody = @"Wake up, man"; notification.alertAction = NSLocalizedString(@"起床了", nil); // 通知提示音 使用默认的 notification.soundName= UILocalNotificationDefaultSoundName; // 设置应用程序右上角的提醒个数 notification.applicationIconBadgeNumber++; // 设定通知的userInfo,用来标识该通知 NSMutableDictionary *aUserInfo = [[NSMutableDictionary alloc] init]; aUserInfo[kLocalNotificationID] = @"LocalNotificationID"; notification.userInfo = aUserInfo; // 将通知添加到系统中 [[UIApplication sharedApplication] scheduleLocalNotification:notification]; }
上面的alertBody是设备收到本地通知时横额或锁屏时的主要文字内容,alertActions是锁屏时显示的slide to后面的文字内容。例如:
repeatInterval表示通知的重复间隔,在SDK中定义如下:
@property(nonatomic) NSCalendarUnit repeatInterval; // 0 means don‘t repeat
其取值主要有:
NSCalendarUnitEra = kCFCalendarUnitEra, NSCalendarUnitYear = kCFCalendarUnitYear, NSCalendarUnitMonth = kCFCalendarUnitMonth, NSCalendarUnitDay = kCFCalendarUnitDay, NSCalendarUnitHour = kCFCalendarUnitHour, NSCalendarUnitMinute = kCFCalendarUnitMinute, NSCalendarUnitSecond = kCFCalendarUnitSecond, NSCalendarUnitWeekday = kCFCalendarUnitWeekday, NSCalendarUnitWeekdayOrdinal = kCFCalendarUnitWeekdayOrdinal,
分别表示一个世纪、一年、一个月等等,0表示不重复。具体可以查看CFCalendar Reference
repeatInterval的下限应该是NSCalendarUnitMinute,即每分钟重复发送一次通知。
如果设置为NSCalendarUnitSecond,那么消息不会重复,每秒发送一次通知,iOS系统当然不会容许这样的存在了。
这里比较不好的一点是该值不能自定义(很遗憾,NSCalendarUnit是个枚举类型),例如你不能塞个10.0给它从而希望它每十秒重复一次。所以如果你想每20分钟发送一次通知,一小时内发送3次,那么只能同时设定三个通知了。
上面的代码运行后,5秒钟之后就可以收到一个本地通知。
在收到通知后,调用程序委托中的下列方法处理:
-(void)application:(UIApplication *)application didReceiveLocalNotification:(UILocalNotification *)notification{ NSLog(@"Application did receive local notifications"); UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Hello" message:@"welcome" delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil, nil]; [alert show]; }
注意这个方法只有在程序启动之后才会执行,因此当程序处于后台时,该方法不会执行。
有一点需要注意,如果我们的应用程序给系统发送的本地通知是周期性的,那么即使把程序删了重装,之前的本地通知在重装时依然存在(没有从系统中移除)。例如,我们在viewDidLoad方法中启动添加本地通知的方法,多跑几次,然后把程序在模拟器中删除,再重新跑,并用下列方法输出所有的本地通知:
NSArray *localNotifications = [[UIApplication sharedApplication] scheduledLocalNotifications]; NSLog(@"%@", localNotifications);
控制台输出:
2014-03-14 15:46:37.145 LocalNotificationDemo[4419:60b] ( "<UIConcreteLocalNotification: 0xa32ce30>{fire date = Friday, March 14, 2014 at 3:38:16 PM China Standard Time, time zone = Asia/Chongqing (GMT+8) offset 28800, repeat interval = NSDayCalendarUnit, repeat count = UILocalNotificationInfiniteRepeatCount, next fire date = Saturday, March 15, 2014 at 3:38:16 PM China Standard Time, user info = {\n ClockID = LocalNotificationID;\n}}", "<UIConcreteLocalNotification: 0xa32dfc0>{fire date = Friday, March 14, 2014 at 3:44:45 PM China Standard Time, time zone = Asia/Chongqing (GMT+8) offset 28800, repeat interval = NSDayCalendarUnit, repeat count = UILocalNotificationInfiniteRepeatCount, next fire date = Saturday, March 15, 2014 at 3:44:45 PM China Standard Time, user info = {\n ClockID = LocalNotificationID;\n}}", "<UIConcreteLocalNotification: 0xa32e470>{fire date = Friday, March 14, 2014 at 3:44:55 PM China Standard Time, time zone = Asia/Chongqing (GMT+8) offset 28800, repeat interval = NSDayCalendarUnit, repeat count = UILocalNotificationInfiniteRepeatCount, next fire date = Saturday, March 15, 2014 at 3:44:55 PM China Standard Time, user info = {\n ClockID = LocalNotificationID;\n}}", "<UIConcreteLocalNotification: 0xa32e950>{fire date = Friday, March 14, 2014 at 3:45:13 PM China Standard Time, time zone = Asia/Chongqing (GMT+8) offset 28800, repeat interval = NSDayCalendarUnit, repeat count = UILocalNotificationInfiniteRepeatCount, next fire date = Saturday, March 15, 2014 at 3:45:13 PM China Standard Time, user info = {\n ClockID = LocalNotificationID;\n}}", "<UIConcreteLocalNotification: 0xa32edb0>{fire date = Friday, March 14, 2014 at 3:45:29 PM China Standard Time, time zone = Asia/Chongqing (GMT+8) offset 28800, repeat interval = NSDayCalendarUnit, repeat count = UILocalNotificationInfiniteRepeatCount, next fire date = Saturday, March 15, 2014 at 3:45:29 PM China Standard Time, user info = {\n ClockID = LocalNotificationID;\n}}", "<UIConcreteLocalNotification: 0xa32e870>{fire date = Friday, March 14, 2014 at 3:46:28 PM China Standard Time, time zone = Asia/Chongqing (GMT+8) offset 28800, repeat interval = NSDayCalendarUnit, repeat count = UILocalNotificationInfiniteRepeatCount, next fire date = Saturday, March 15, 2014 at 3:46:28 PM China Standard Time, user info = {\n ClockID = LocalNotificationID;\n}}" )
可以看到之前发送的本地通知一直滞留在系统中。
不只是模拟器,在iOS设备上也是这样,博主之前的App在设备上重装时以前的本地通知会继续发送。
因此我们需要取消通知的方法,当然该对象也会在scheduledLocalNotifications数组中移除。
取消方法分为两种。
第一种比较暴力,直接取消所有的本地通知:
[[UIApplication sharedApplication] cancelAllLocalNotifications];
这个适合在App重装时第一次启动的时候,或还原程序默认设置等场合下使用。
第二种方法是针对某个特定通知的:
- (void)cancelLocalNotification:(UILocalNotification *)notification NS_AVAILABLE_IOS(4_0);
这时就需要通知有一个标识,这样我们才能定位是哪一个通知。可以在notification的userInfo(一个字典)中指定。
例如:
-(void)application:(UIApplication *)application didReceiveLocalNotification:(UILocalNotification *)notification{ NSLog(@"Application did receive local notifications"); // 取消某个特定的本地通知 for (UILocalNotification *noti in [[UIApplication sharedApplication] scheduledLocalNotifications]) { NSString *notiID = noti.userInfo[kLocalNotificationID]; NSString *receiveNotiID = notification.userInfo[kLocalNotificationID]; if ([notiID isEqualToString:receiveNotiID]) { [[UIApplication sharedApplication] cancelLocalNotification:notification]; return; } } UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Hello" message:@"welcome" delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil, nil]; [alert show]; }
最后建议本地通知不要发得太频繁,不然用户会觉得非常的烦。
参考的文章和资料:
iOS: 枚举类型 enum,NS_ENUM,NS_OPTIONS
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