iOS 发送本地推送通知

App在后台的情况希望通知用户看到信息时使用本地推送通知实现。
1.导入系统框架

#import <UserNotifications/UserNotifications.h>

2.注册本地通知样式

UIApplication* application = [UIApplication sharedApplication];
    if ([application currentUserNotificationSettings]) {
      UIUserNotificationSettings* setting = [UIUserNotificationSettings
          settingsForTypes:UIUserNotificationTypeBadge |
                           UIUserNotificationTypeSound |
                           UIUserNotificationTypeAlert
                categories:nil];
      [application registerUserNotificationSettings:setting];
    }

3.清除之前注册通知

[application cancelAllLocalNotifications];

如果不清除历史通知，可能会收到之前的全部通知。
4.设置本次通知内容

UILocalNotification* localNotif = [[UILocalNotification alloc] init];
// 发送时间
    localNotif.fireDate =[NSDate dateWithTimeIntervalSinceNow:0];
// 在通知中心要展示的通知内容
    localNotif.alertBody = @"本地推送通知";
// 通知携带的内容信息，开发者自行处理
    localNotif.userInfo = @{@"userid":@(123), @"message":@"通知"};
// 自定义同事提示声音，必须是.caf格式音频文件
    localNotif.soundName = @"voip_call.caf";
// 本次通知的事件标识
    localNotif.alertAction = @"notificationKey";
    [application scheduleLocalNotification:localNotif];

以上方法在 iOS10之后被弃用，iOS 开始使用UNUserNotificationCenter
具体逻辑大概类似。UNUserNotificationCenter的内容更加丰富，可以通过它自行定义通知显示样式，功能更加强大。

UNUserNotificationCenter* center =
      [UNUserNotificationCenter currentNotificationCenter];
  UNMutableNotificationContent* content =
      [[UNMutableNotificationContent alloc] init];
  content.body =  @"本地推送通知";
  UNNotificationSound* sound =
      [UNNotificationSound soundNamed:@"voip_call.caf"];
  content.sound = sound;
  content.userInfo = @{@"userid":@(123), @"message":@"通知"};
  UNTimeIntervalNotificationTrigger* tirgger =
      [UNTimeIntervalNotificationTrigger triggerWithTimeInterval:0.1
                                                         repeats:NO];
  UNNotificationRequest* request =
      [UNNotificationRequest requestWithIdentifier:@"notificationKey"
                                           content:content
                                           trigger:tirgger];

  [center addNotificationRequest:request
           withCompletionHandler:^(NSError* _Nullable error) {
             NSLog(@"%@本地推送 :( 报错 %@", @"notificationKey", error);
           }];

最后接收本地推送通知

- (void)application:(UIApplication*)application
    didReceiveLocalNotification:(UILocalNotification*)notification {
  if (notification &&
      [notification.alertAction isEqualToString:@"notificationKey"]) {
  }
}

iOS10之后
// 点击推送消息后回调

- (void)userNotificationCenter:(UNUserNotificationCenter*)center
    didReceiveNotificationResponse:(UNNotificationResponse*)response
             withCompletionHandler:(void (^)(void))completionHandler {
  NSLog(@"center content : %@", response.notification.request.content.userInfo);
  if (response && [response.notification.request.identifier
                      isEqualToString:@"notificationKey"]) {
  }
}

有时候需要删除通知中心的通知，类似微信撤回消息时会撤回通知

- (void)deleteLocalNotificationForUserId:(int)userId {
  if ([[UIDevice currentDevice].systemVersion doubleValue] >= 10.0) {
    UNUserNotificationCenter* center =
        [UNUserNotificationCenter currentNotificationCenter];
    [center getPendingNotificationRequestsWithCompletionHandler:^(
                NSArray<UNNotificationRequest*>* _Nonnull requests) {
      for (UNNotificationRequest* request in requests) {
        if ([request.identifier isEqualToString:ISAVChatNotification]) {
          NSDictionary* userInfo = request.content.userInfo;
          if (userInfo) {
          }
        }
      }
    }];

    [center
        removeDeliveredNotificationsWithIdentifiers:@[ @"notificationKey" ]];
  } else {
    UIApplication* application = [UIApplication sharedApplication];
    NSArray* localNotifications = [application scheduledLocalNotifications];
    for (UILocalNotification* local in localNotifications) {
      if ([local.alertAction isEqualToString:ISAVChatNotification]) {
        NSDictionary* userInfo = local.userInfo;
        if (userInfo) {
          if (userId == [[friendInfo objectForKey:@"userId"] intValue]) {
            [application cancelLocalNotification:local];
            NSInteger num = [application applicationIconBadgeNumber];
            if (num > 1) {
              [application setApplicationIconBadgeNumber:num - 1];
            } else {
              [application setApplicationIconBadgeNumber:0];
            }
          }
        }
      }
    }
  }
}

mp3转 caf
第一步：获取MP3文件路径，为了方便测试，这里把文件放到了桌面上，地址为 ：/Users/Mina/Desktop/1.mp3

第二步：设置CAF文件的输出路径，这里也放到了桌面上，路径为：/Users/Mina/Desktop/2.caf

第三步：打开终端输入命令：
afconvert /Users/Mina/Desktop/1.mp3 /Users/Mina/Desktop/2.caf -d ima4 -f caff -v
(注：不要忘记空格)