实现软件版本新特性的具体步奏

1、版本新特性：

     控制器的跳转不能使用push 和modal,

     push： 采用的时栈的方式，无法销毁之前的控制器

     modal：无法销毁之前的控制器

    应该使用rootViewController

2、实现过程：

    ①设置滚动视图，一般是整个界面

- (void)setupScrollView
{
    UIScrollView *scrollView = [[UIScrollView alloc] init];
    scrollView.frame = self.view.bounds;
    scrollView.delegate = self;
    [self.view addSubview:scrollView];
    
    // 2.添加图片
    CGFloat imageW = scrollView.frame.size.width;
    CGFloat imageH = scrollView.frame.size.height;
    for (int index = 0; index<IWNewfeatureImageCount; index++) {
        UIImageView *imageView = [[UIImageView alloc] init];
        
        // 设置图片
        NSString *name = [NSString stringWithFormat:@"new_feature_%d", index + 1];
        imageView.image = [UIImage imageWithName:name];
        
        // 设置frame
        CGFloat imageX = index * imageW;
        imageView.frame = CGRectMake(imageX, 0, imageW, imageH);
        
        [scrollView addSubview:imageView];
        
        // 在最后一个图片上面添加按钮
        if (index == IWNewfeatureImageCount - 1) {
            [self setupLastImageView:imageView];
        }
    }
    
    // 3.设置滚动的内容尺寸
    scrollView.contentSize = CGSizeMake(imageW * IWNewfeatureImageCount, 0);
   // 取消水平滚动条 scrollView.showsHorizontalScrollIndicator = NO；
    scrollView.pagingEnabled = YES;
// 取消滚动的弹簧效果   
  scrollView.bounces = NO;
}

        ②设置分页，求出分页的页码，需要使用UIScrollView的代理，使用代理方法

// 1.添加
    UIPageControl *pageControl = [[UIPageControl alloc] init];
    pageControl.numberOfPages = IWNewfeatureImageCount;
    CGFloat centerX = self.view.frame.size.width * 0.5;
    CGFloat centerY = self.view.frame.size.height - 30;
    pageControl.center = CGPointMake(centerX, centerY);
    pageControl.bounds = CGRectMake(0, 0, 100, 30);
    pageControl.userInteractionEnabled = NO;
    [self.view addSubview:pageControl];
    self.pageControl = pageControl;
    
    // 2.设置圆点的颜色
    pageControl.currentPageIndicatorTintColor = IWColor(253, 98, 42);
    pageControl.pageIndicatorTintColor = IWColor(189, 189, 189);
②求出分页的页码，需要使用UIScrollView的代理，使用代理方法
/**
 *  只要UIScrollView滚动了,就会调用
 *
 */
- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
    // 1.取出水平方向上滚动的距离
    CGFloat offsetX = scrollView.contentOffset.x;
    
    // 2.求出页码
    double pageDouble = offsetX / scrollView.frame.size.width;
    int pageInt = (int)(pageDouble + 0.5);
    self.pageControl.currentPage = pageInt;
}

    ③在最后一张图片添加按钮，跳转控制器

- (void)setupLastImageView:(UIImageView *)imageView
{
    // 0.让imageView能跟用户交互
    imageView.userInteractionEnabled = YES;
    
    // 1.添加开始按钮
    UIButton *startButton = [[UIButton alloc] init];
    [startButton setBackgroundImage:[UIImage imageWithName:@"new_feature_finish_button"] forState:UIControlStateNormal];
    [startButton setBackgroundImage:[UIImage imageWithName:@"new_feature_finish_button_highlighted"] forState:UIControlStateHighlighted];
    
    // 2.设置frame
    CGFloat centerX = imageView.frame.size.width * 0.5;
    CGFloat centerY = imageView.frame.size.height * 0.6;
    startButton.center = CGPointMake(centerX, centerY);
    startButton.bounds = (CGRect){CGPointZero, startButton.currentBackgroundImage.size};
    
    // 3.设置文字
    [startButton setTitle:@"开始使用" forState:UIControlStateNormal];
    [startButton setTitleColor:[UIColor whiteColor] forState:UIControlStateNormal];
    [startButton addTarget:self action:@selector(start) forControlEvents:UIControlEventTouchUpInside];
    [imageView addSubview:startButton];
    
    // 4.添加checkbox
    UIButton *checkbox = [[UIButton alloc] init];
    checkbox.selected = YES;
    [checkbox setTitle:@"分享给大家" forState:UIControlStateNormal];
    [checkbox setImage:[UIImage imageWithName:@"new_feature_share_false"] forState:UIControlStateNormal];
    [checkbox setImage:[UIImage imageWithName:@"new_feature_share_true"] forState:UIControlStateSelected];
    checkbox.bounds = CGRectMake(0, 0, 200, 50);
    CGFloat checkboxCenterX = centerX;
    CGFloat checkboxCenterY = imageView.frame.size.height * 0.5;
    checkbox.center = CGPointMake(checkboxCenterX, checkboxCenterY);
    [checkbox setTitleColor:[UIColor blackColor] forState:UIControlStateNormal];
    checkbox.titleLabel.font = [UIFont systemFontOfSize:15];
    [checkbox addTarget:self action:@selector(checkboxClick:) forControlEvents:UIControlEventTouchUpInside];
    checkbox.imageEdgeInsets = UIEdgeInsetsMake(0, 0, 0, 10);
    [imageView addSubview:checkbox];
}
④点击开始使用时候，切换根控制器
- (void)start
{
    // 显示状态栏
    [UIApplication sharedApplication].statusBarHidden = NO;
    // 切换窗口的根控制器
    self.view.window.rootViewController = [[IWTabBarViewController alloc] init];
}

 ④利用沙盒，将使用的软件版本号与沙盒中存储的版本号进行对比，高于原版本就跳转到 IWNewfeatureViewController ，相同就跳转到IWTabBarViewController：

 NSString *key = @"CFBundleVersion";
    
    // 取出沙盒中存储的上次使用软件的版本号
    NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
    NSString *lastVersion = [defaults stringForKey:key];
    
    // 获得当前软件的版本号
    NSString *currentVersion = [NSBundle mainBundle].infoDictionary[key];
    
    if ([currentVersion isEqualToString:lastVersion]) {
        // 显示状态栏
        application.statusBarHidden = NO;
        
        self.window.rootViewController = [[IWTabBarViewController alloc] init];
    } else { // 新版本
        self.window.rootViewController = [[IWNewfeatureViewController alloc] init];
        // 存储新版本
        [defaults setObject:currentVersion forKey:key];
        [defaults synchronize];
    }