iOS本地通知：UILocalNotification
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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：
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// 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];
}
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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：
<喎�"http://www.2cto.com/kf/ware/vc/" target="_blank" class="keylink">vcD4KPHByZSBjbGFzcz0="brush:java;">@property(nonatomic) NSCalendarUnit repeatInterval; // 0 means don't repeat
其取值主要有：
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NSCalendarUnitEra = kCFCalendarUnitEra,
NSCalendarUnitYear = kCFCalendarUnitYear,
NSCalendarUnitMonth = kCFCalendarUnitMonth,
NSCalendarUnitDay = kCFCalendarUnitDay,
NSCalendarUnitHour = kCFCalendarUnitHour,
NSCalendarUnitMinute = kCFCalendarUnitMinute,
NSCalendarUnitSecond = kCFCalendarUnitSecond,
NSCalendarUnitWeekday = kCFCalendarUnitWeekday,
NSCalendarUnitWeekdayOrdinal = kCFCalendarUnitWeekdayOrdinal,
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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：
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-(
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];
}
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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：
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NSArray *localNotifications = [[UIApplication sharedApplication] scheduledLocalNotifications];
NSLog(@
"%@"
, localNotifications);
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控制台输出：
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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}}"
)</uiconcretelocalnotification:></uiconcretelocalnotification:></uiconcretelocalnotification:></uiconcretelocalnotification:></uiconcretelocalnotification:></uiconcretelocalnotification:>
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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：
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[[UIApplication sharedApplication] cancelAllLocalNotifications];
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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：
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- (
void
)cancelLocalNotification:(UILocalNotification *)notification NS_AVAILABLE_IOS(4_0);
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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：
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-(
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];
}
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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。