[翻譯]計劃，註冊處理系統通知（Notifications）的步驟

本章描述ios系統中計劃local notification,註冊 remote notification,以及處理 local和remote notification的步驟。本文中客戶端API中notification推送指的就是remote notfication的推送

第一個知識點：準備我的定製音頻做爲提示音,

請注意下面四個小問題-----

1，
系統能播放的四種音頻數據格式
Linear PCM
MA4 (IMA/ADPCM)
µLaw
aLaw
對應的後綴名能夠是aiff, wav, or caf file. Then, 
2， 能夠用afconvert來轉換音頻，例如把16位的線性PCM系統音頻格式文件 Submarine.aiff 轉換成IMA4音頻，存爲.CAF文件。
在終端執行便可
afconvert /System/Library/Sounds/Submarine.aiff ~/Desktop/sub.caf -d ima4 -f caff -v
3， 如何肯定音頻格式呢。
打開QuickTime Player-> Movie menu->Show Movie Inspector 
4， 我的定製音頻必須是30s如下。不然就播放默認的聲音了。

第二個知識點：預約一個Local Notification
須要瞭解下面5個步驟
1， Allocate 和 initialize 一個 UILocalNotification對象。
2， fireDate屬性賦值
3， 設置別的幾個體型要素 提示框，提示音，圖標上的提示數字。也能夠帶別的個性化數據：經過userInfo帶出去。
4， 而後Schedule這個通知。經過UIApplication.scheduleLocalNotification來預約執行或者立馬執行presentLocalNotificationNow：
5， 也能夠取消這個通知。用這個方法：cancelLocalNotification和cancelAllLocalNotifications這個方法

看下代碼
//如何建立設定一個Notification
- (void)scheduleNotificationWithItem:(ToDoItem *)item interval:(int)minutesBefore {
    NSCalendar *calendar = [NSCalendar autoupdatingCurrentCalendar];
    NSDateComponents *dateComps = [[NSDateComponents alloc] init];
    [dateComps setDay:item.day];
    [dateComps setMonth:item.month];
    [dateComps setYear:item.year];
    [dateComps setHour:item.hour];
    [dateComps setMinute:item.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:NSLocalizedString(@"%@ in %i minutes.", nil),
         item.eventName, minutesBefore];
    localNotif.alertAction = NSLocalizedString(@"View Details", nil);
 
    localNotif.soundName = UILocalNotificationDefaultSoundName;
    localNotif.applicationIconBadgeNumber = 1;
 
    NSDictionary *infoDict = [NSDictionary dictionaryWithObject:item.eventName forKey:ToDoItemKey];
    localNotif.userInfo = infoDict;
 
    [[UIApplication sharedApplication] scheduleLocalNotification:localNotif];
    [localNotif release];
}




//程序運行在後臺時候如何提交一個UILocalNotification。
- (void)applicationDidEnterBackground:(UIApplication *)application {
    NSLog(@"Application entered background state.");
    // bgTask is instance variable
    NSAssert(self->bgTask == UIInvalidBackgroundTask, nil);
 
    bgTask = [application beginBackgroundTaskWithExpirationHandler: ^{
        dispatch_async(dispatch_get_main_queue(), ^{
            [application endBackgroundTask:self->bgTask];
            self->bgTask = UIInvalidBackgroundTask;
        });
    }];
 
    dispatch_async(dispatch_get_main_queue(), ^{
        while ([application backgroundTimeRemaining] > 1.0) {
            NSString *friend = [self checkForIncomingChat];
            if (friend) {
                UILocalNotification *localNotif = [[UILocalNotification alloc] init];
                if (localNotif) {
                    localNotif.alertBody = [NSString stringWithFormat:
                        NSLocalizedString(@"%@ has a message for you.", nil), friend];
                    localNotif.alertAction = NSLocalizedString(@"Read Message", nil);
                    localNotif.soundName = @"alarmsound.caf";
                    localNotif.applicationIconBadgeNumber = 1;
                    [application presentLocalNotificationNow:localNotif];
                    [localNotif release];
                    friend = nil;
                    break;
                }
            }
        }
        [application endBackgroundTask:self->bgTask];
        self->bgTask = UIInvalidBackgroundTask;
    });
 
}

第三個知識點：註冊 Remote Notifications

須要註冊Apple Push Notification service ，有三步
1，調用 registerForRemoteNotificationTypes:方法
2，經過實現application:didRegisterForRemoteNotificationsWithDeviceToken:這個delegate來接受從APNs傳過來的device token。這個token是個binary的值
3，程序啓動即需調用theregisterForRemoteNotificationTypes: 方法來註冊推送。後期能夠調用enabledRemoteNotificationTypes這個方法來改通知類型。
須要注意的事情：
若是網絡不通，application:didRegisterForRemoteNotificationsWithDeviceToken這個方法和application:didFailToRegisterForRemoteNotificationsWithError:都不會被調用哦。Wifi的時候，經過5223端口連接APNs一般連不上喲由於網管把端口封掉了喲。
 
看下代碼：
Listing 2-3  Registering for remote notifications
- (void)applicationDidFinishLaunching:(UIApplication *)app {
   // other setup tasks here....
    [[UIApplication sharedApplication] registerForRemoteNotificationTypes:(UIRemoteNotificationTypeBadge | UIRemoteNotificationTypeSound)];
}
 
// Delegation methods
- (void)application:(UIApplication *)app didRegisterForRemoteNotificationsWithDeviceToken:(NSData *)devToken {
    const void *devTokenBytes = [devToken bytes];
    self.registered = YES;
    [self sendProviderDeviceToken:devTokenBytes]; // custom method
}
 
- (void)application:(UIApplication *)app didFailToRegisterForRemoteNotificationsWithError:(NSError *)err {
    NSLog(@"Error in registration. Error: %@", err);

}

第四個知識點：處理 Local and Remote Notifications
通常通知來時，程序有兩種狀態。
1，後臺運行發送，須要窗體，聲音和數字
點擊窗體，啓動程序。程序啓動了在application:didFinishLaunchingWithOptions: 方法裏面獲取傳遞的數據
notification payload (for remote notifications) or 
local-notification object (for local notifications).


2，程序在前臺跑着呢。
程序直接就調用application:didReceiveRemoteNotification:  (for remote notifications)這個方法了
 application:didReceiveLocalNotification: method (for local notifications)


總之要實現UIApplicationDelegate協議
實現application:didFinishLaunchingWithOptions:方法
實現application:didReceiveRemoteNotification:方法
或者實現application:didReceiveLocalNotification:方法


3，那如何判斷區別前臺仍是後臺這兩種情況呢。


用這個屬性applicationState來判斷。
若爲UIApplicationStateInactive就是用戶點擊通知框按鈕進來的。
若爲UIApplicationStateActive，就是前臺正跑着呢。


看下代碼


//Handling a local notification when an application is launched
- (BOOL)application:(UIApplication *)app didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
    UILocalNotification *localNotif =
        [launchOptions objectForKey:UIApplicationLaunchOptionsLocalNotificationKey];
    if (localNotif) {
        NSString *itemName = [localNotif.userInfo objectForKey:ToDoItemKey];
        [viewController displayItem:itemName];  // custom method
        application.applicationIconBadgeNumber = localNotif.applicationIconBadgeNumber-1;
    }
    [window addSubview:viewController.view];
    [window makeKeyAndVisible];
    return YES;
}




這裏能夠經過UIApplicationLaunchOptionsRemoteNotificationKey來獲取通知傳遞過來的自定義數據




以後便可從provider方下數據了。
- (void)application:(UIApplication *)app didFinishLaunchingWithOptions:(NSDictionary *)opts {
    // check launchOptions for notification payload and custom data, set UI context
    [self startDownloadingDataFromProvider];  // custom method
    app.applicationIconBadgeNumber = 0;
    // other setup tasks here....
}


Listing 2-6  Handling a local notification when an application is already running
- (void)application:(UIApplication *)app didReceiveLocalNotification:(UILocalNotification *)notif {
    NSString *itemName = [notif.userInfo objectForKey:ToDoItemKey]
    [viewController displayItem:itemName];  // custom method
    application.applicationIconBadgeNumber = notification.applicationIconBadgeNumber-1;
}

本文爲意譯，原文地址：https://developer.apple.com/library/ios/#documentation/NetworkingInternet/Conceptual/RemoteNotificationsPG/IPhoneOSClientImp/IPhoneOSClientImp.html#//apple_ref/doc/uid/TP40008194-CH103-SW1