设置app右上角的角标数字，设置为0，则不显示
//开启用户权限，否则不会显示
NSString * version = [UIDevice currentDevice].systemVersion;
if ([version floatValue] >= 8.0) {
UIUserNotificationSettings * set = [UIUserNotificationSettings settingsForTypes:UIUserNotificationTypeBadge categories:nil];
[[UIApplication sharedApplication] registerUserNotificationSettings:set];
[[UIApplication sharedApplication] registerForRemoteNotifications];
}
//设置显示数字
[[UIApplication sharedApplication] setApplicationIconBadgeNumber:10];
该方法一般放在当app退到后台挂起时，所以应当放在app生命周期的方法中
- (void)applicationDidEnterBackground:(UIApplication *)application {
}
