NSCalendar * calendar = [NSCalendar autoupdatingCurrentCalendar];
NSDateComponents * dateComponent = [NSDateComponents alloc] init];
[dateComponent setDay: item.day]; // item: self defined object
[dateComponent setMonth: item.month];
[dateComponent setYear: item.year];
[dateComponent setHour: item.hour];
[dateComponent setMinute: item.minute];
NSDate * date = [calendar dateFromComponents: dateComponent];
UILocalNotification *localNotif = [[UILocalNotification alloc] init];
if (localNotif == nil)
return;
localNotif.fireDate =
[date
dateByAddingTimeIntervalInterval:-(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.alerttitle = NSLocalizedString(@"Item Due", nil);
localNotif.soundName = UILocalNotificationDefaultSoundName;
localNotif.applicationIconBadgeNumber = 1;
NSDictionary *infoDict = [NSDictionary dictionaryWithObject:item.eventName
forKey:ToDoItemKey];
localNotif.userInfo = infoDict;
[[UIApplication sharedApplication] scheduleLocalNotification:localNotif];
那麼要設定Push Notification要怎麼做？首先要用Apple的Push Notification機制（簡稱APN），自己的Server發出通知後會傳到Apple的Server，之後再從Apple傳給使用者的App：
我覺得這樣做的原因是要保持通知的完整性和安全性，假如說你傳送有惡意訊息的封包給使用者豈不是不好？而建立整個連線流程如下圖所示，裝置先和APN建立TLS（Transport Layer Security）連線，之後取得憑證後TLS就算建立完成：
而Provider也是同樣要建立TLS連線和取得憑證：
而當憑證建立完成後App和APN, Provider的互動就是靠Token來完成，App若要使用Push Notificaition必須先行註冊至APN（從使用者那邊獲取通知許可），然後APN再回傳加密過的Token給Provider，之後該Token再從Device回傳到Provider，如下圖所示：
而在傳送Push Notification時會連同Token，並藉由裝置ID來回傳加密的通知內容給裝置：
到這邊整個Push Notification就算完成，接下來就是在AppDelegate.m加上程式碼：
另外當收到了Notification後要做什麼事就先靠didReceiveRemoteNotification來完成，而handleActionWithIdentifier則是當使用者對Notification做出回應後你要採取什麼動作時，可用completionHandler的block來完成：// Remote notifications- (void)application:(UIApplication *)application didRegisterForRemoteNotificationsWithDeviceToken:(NSData *)deviceToken{NSLog(@"Receive deviceToken: %@", deviceToken);}- (void)application:(UIApplication *)application didFailToRegisterForRemoteNotificationsWithError:(NSError *)error{NSLog(@"Remote notification error: %@", error.localizedDescription);}
// When app is waked up, this method will be called- (void)application:(UIApplication *)application didReceiveRemoteNotification:(NSDictionary *)userInfo fetchCompletionHandler:(void (^)(UIBackgroundFetchResult))completionHandler{// with push notification from remote server// When app is running in the foreground, this method will be called}
- (void)application:(UIApplication *)application handleActionWithIdentifier:(NSString *)identifier forRemoteNotification:(NSDictionary *)userInfo completionHandler:(void (^)())completionHandler{// Test for identifier with a sample indentifierif ([identifier isEqualToString:@"ACCEPT_IDENTIFIER"]) {[self handleAcceptActionWithNotification:userInfo];}}
以上就是整個流程，至於說要註冊憑證的方法可參考這篇：popcorny的碎碎念
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