IOS App 右上脚红色数字提醒

IOS8.0以前直接显示：

UIApplication *application=[UIApplication sharedApplication];
 //设置图标上的更新数字
 application.applicationIconBadgeNumber=3;

IOS8.0以后需加上以下代码让用户选择是否显示

float versionNumber=[[[UIDevice currentDevice] systemVersion] floatValue];

if (versionNumber >= 8.0) {//通知设置
    UIUserNotificationSettings *settings = [UIUserNotificationSettings settingsForTypes:UIUserNotificationTypeBadge categories:nil];
    //接收用户的选择
    [[UIApplication sharedApplication] registerUserNotificationSettings:settings];
}

类似下面效果：