第一次新特性

判断是否是第一次打开该版本
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    application.statusBarHidden = NO;
    
    // 1.创建窗口
    self.window = [[UIWindow alloc] init];
    self.window.frame = [UIScreen mainScreen].bounds;
    
    // 2.设置窗口的根控制器
    // 如何知道第一次使用这个版本？比较上次的使用情况
    //NSString *versionKey = @"CFBundleVersion";
    NSString *versionKey = (__bridge NSString *)kCFBundleVersionKey;
    
    // 从沙盒中取出上次存储的软件版本号(取出用户上次的使用记录)
    NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
    NSString *lastVersion = [defaults objectForKey:versionKey];
    
    // 获得当前打开软件的版本号
    NSString *currentVersion = [NSBundle mainBundle].infoDictionary[versionKey];
    
    if ([currentVersion isEqualToString:lastVersion]) { // 当前版本号 == 上次使用的版本：显示HMTabBarViewController
        self.window.rootViewController = [[SNTabBarViewController alloc] init];
    } else { // 当前版本号 != 上次使用的版本：显示版本新特性
        self.window.rootViewController = [[SNNewfeatureViewController alloc] init];
        
        // 存储这次使用的软件版本
        [defaults setObject:currentVersion forKey:versionKey];
        [defaults synchronize];
    }

    // 3.显示窗口(成为主窗口)
    [self.window makeKeyAndVisible];
    return YES;
}

现实新特性
#define SNNewfeatureImageCount 4

#import "SNNewfeatureViewController.h"

@interface SNNewfeatureViewController () <UIScrollViewDelegate>

@property (nonatomic, weak)UIPageControl *pageControl;

@end

@implementation SNNewfeatureViewController

- (void)viewDidLoad
{
    [super viewDidLoad];
   
    //1.添加UISrollView
    [self setupScrollView];
    
    //2.添加pageControl
    [self setupPageControl];

}

-(void)setupScrollView
{
    //1.添加UISrollView
    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.width;
    CGFloat imageH = scrollView.height;
    for (int i = 0; i<SNNewfeatureImageCount; i++) {
        //图片
        UIImageView *imageView = [[UIImageView alloc]init];
        NSString *name = [NSString stringWithFormat:@"new_feature_%d", i+1];
        if (FourInch) {
            name = [name stringByAppendingString:@"-568h"];
        }
        imageView.image = [UIImage imageNamed:name];
        [scrollView addSubview:imageView];
        
        //设置frame
        imageView.y = 0;
        imageView.width = imageW;
        imageView.height = imageH;
        imageView.x = i * imageW;
        
        //给最后一个imageView添加按钮
        
    }
    
    //3.设置其他属性
    //总长度
    scrollView.contentSize = CGSizeMake(imageW * SNNewfeatureImageCount, 0);
    //要么不切换，要么切换一屏
    scrollView.pagingEnabled = YES;
    //隐藏滚动条
    scrollView.showsHorizontalScrollIndicator = NO;
    //没有回弹效果
    //scrollView.bounces = NO;
    //回弹，背景色
    scrollView.backgroundColor = SNColor(246, 246, 246);
}


-(void)setupPageControl
{
    //1.添加
    UIPageControl *pageControl = [[UIPageControl alloc]init];
    pageControl.numberOfPages = SNNewfeatureImageCount;
    pageControl.centerX = self.view.width * 0.5;
    pageControl.centerY = self.view.height - 30;
    [self.view addSubview:pageControl];
    
    
    //2.设置圆点颜色
    pageControl.currentPageIndicatorTintColor = SNColor(253, 98, 42);
    pageControl.pageIndicatorTintColor = SNColor(189, 189, 189);
    self.pageControl = pageControl;
}


#pragma mark - UIScrollViewDelegate
-(void)scrollViewDidScroll:(UIScrollView *)scrollView
{
    //获得页码
    CGFloat doublePage = scrollView.contentOffset.x / scrollView.width;
    int intPage = (int)(doublePage + 0.5);
    //设置页码
    self.pageControl.currentPage = intPage;
}
@end