新特性界面

1.当第一次安装或版本升级时显示新特性界面

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
    
     // 1.创建window
    self.window = [[UIWindow alloc]initWithFrame:[UIScreen mainScreen].bounds];
    self.window.backgroundColor = [UIColor whiteColor];
    
    // 2.根据版本号判断是否选择新特性
    [self checkNewFeatureVC];
    
    // 3.显示window
    [self.window makeKeyAndVisible];
    
    return YES;
}

- (void)checkNewFeatureVC{
    // 2-1.获取软件自身版本
    NSDictionary *infoDict = [NSBundle mainBundle].infoDictionary;
    NSString *currentVersion = infoDict[@"CFBundleShortVersionString"];
    
    // 2-2.获取沙盒中存储的版本号
    NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
    NSString *sandboxVersion = [defaults objectForKey:@"oldVersion"];
    
    // 2-3.比较两个版本号,如果软件自身大于沙盒的,保存软件自身的,显示新特性
    
    if([currentVersion compare:sandboxVersion] == NSOrderedDescending){//当前系统版本号和沙盒版本号比较,如果降序
        self.window.rootViewController = [[NewFeatureViewController alloc]init];
        
        //2-4.将新版本号保存到沙盒
        [[NSUserDefaults standardUserDefaults]setObject:currentVersion forKey:@"oldVersion"];
        
    }else{
        self.window.rootViewController = [[ViewController alloc]init];
    }

}