怎么使ios上方通知栏清空本应用的所有通知消息？

int badgeCount = [UIApplication sharedApplication].applicationIconBadgeNumber; 
[[UIApplication sharedApplication] setApplicationIconBadgeNumber:0]; 
[[UIApplication sharedApplication] cancelAllLocalNotifications]; 
[[UIApplication sharedApplication] setApplicationIconBadgeNumber:badgeCount]