棋盘

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {

    

    _window = [[UIWindowalloc]initWithFrame:[UIScreenmainScreen].bounds];

    _window.backgroundColor = [UIColorwhiteColor];

    [_windowmakeKeyAndVisible];

    

    for (int j =0; j <15; j ++) {

        for (int i =0; i <10; i ++) {

            UIView *view = [[UIViewalloc]initWithFrame:CGRectMake(20 * i, (20 * j)+20,20,20)];

            if ((i + j) % 2 == 0) {

                view.backgroundColor = [UIColorredColor];

            }else{

                view.backgroundColor = [UIColorblackColor];

            }

            [_window addSubview:view];

        }

    }

    

    

    return YES;

}

最终效果