iOS:新特性展示

+ (void)choseRootVC
{
    NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
    NSString *saveVersion = [defaults objectForKey:@"CFBundleVersion"];
    NSString *currentVersion = [NSBundle mainBundle].infoDictionary[@"CFBundleVersion"];
    if ([saveVersion isEqualToString:currentVersion]) {//两个版本号相同，不是第一次使用这个软件
        IWTabBarController *main = [[IWTabBarController alloc]init];
        [UIApplication sharedApplication].keyWindow.rootViewController = main;
    }else//版本号不同，第一次使用这个软件
    {
        IWNewfeatureViewController *newfeature = [[IWNewfeatureViewController alloc]init];
        [UIApplication sharedApplication].keyWindow.rootViewController = newfeature;
    }
}