将旧的推送通知从通知中心移除掉

1.将app的BadgeNumber设为0，就是app图标右上角那个

[[UIApplication sharedApplication] setApplicationIconBadgeNumber:0];

2.如果BadgeNumber本身就是0的情况，可以先将其设1再设置成0

[[UIApplication sharedApplication] setApplicationIconBadgeNumber:1];
[[UIApplication sharedApplication] setApplicationIconBadgeNumber:0];

3.如果以上的办法都不好使的话，那就用本地通知欺骗一下。

UIApplication* application = [UIApplication sharedApplication];
NSArray* scheduledNotifications = [NSArray arrayWithArray:application.scheduledLocalNotifications];
application.scheduledLocalNotifications = scheduledNotifications;