UILocalNotification每分钟重复

我想每隔一分钟发送本地通知，写出的代码：

[[UIApplication sharedApplication] cancelAllLocalNotifications];

    UILocalNotification *notif = [[UILocalNotification alloc] init];

    if (notif == nil) {
        return;
    }

    notif.timeZone = [NSTimeZone defaultTimeZone];

    notif.alertBody = @"Test notification!";
    notif.alertAction = @"View";
    notif.soundName = UILocalNotificationDefaultSoundName;
    notif.applicationIconBadgeNumber += 1;

    notif.repeatInterval = NSMinuteCalendarUnit;

    [[UIApplication sharedApplication] scheduleLocalNotification:notif];

但是它只发送一次就不再发送了。不知道怎么改。