- (void)viewDidLoad {

    [super viewDidLoad];

    // Do any additional setup after loading the view, typically from a nib.

    UIScrollView *scrollView = [[UIScrollView alloc] initWithFrame:kScreenBounds];

    scrollView.backgroundColor = [UIColor yellowColor];

    [self.view addSubview:scrollView];

    UIButton *button = [UIButton buttonWithType:UIButtonTypeSystem];

    button.backgroundColor = [UIColor blueColor];

    button.frame = CGRectMake(, , kScreenWidth - , );

    [scrollView addSubview:button];

    // 1. 默认 CGSizeZero == CGSizeMake(0, 0)

    // contentSize 设置可以滚动的范围

    scrollView.contentSize = CGSizeMake(, );

    // 2. 默认 CGPointZero

    // contentOffset 偏移量, 滚动的位置

    // 不设置contentSize, contentOffset也可以改变

    // 问题: 改变contentOffset什么变了?

    // 答案: 改变contentOffset, 实质上是对scrollView的bounds进行了改变.(改变子视图的坐标)

    NSLog(@"scrollView frame is : %@", NSStringFromCGRect(scrollView.frame));

    NSLog(@"scrollView bounds is : %@", NSStringFromCGRect(scrollView.bounds));

    scrollView.contentOffset = CGPointMake(, );

    NSLog(@"scrollView frame is : %@", NSStringFromCGRect(scrollView.frame));

    NSLog(@"scrollView bounds is : %@", NSStringFromCGRect(scrollView.bounds));

    // 3. contentInset

    // 添加滚动区域四周的滚动范围

    // UIEdgeInsets age = {10, 10, 10, 10};

    scrollView.contentInset = UIEdgeInsetsMake(, , , );

    // 4. directionalLockEnabled

    // 锁定垂直或水平滚动(45度角, 锁会失效)

    scrollView.directionalLockEnabled = YES;

    // 5. bounces 回弹效果

    // 边缘弹动动画关闭 NO

    // scrollView.bounces = NO;

    // 6. alwaysBounceVertical 在没有垂直方向的滚动范围时(0), 保证垂直方向的回弹效果

    scrollView.alwaysBounceVertical = YES;

    // 7. alwaysBounceHorizontal 在没有水平方向的滚动范围时(0), 保证垂直方向的回弹效果

    scrollView.alwaysBounceHorizontal = YES;

    // 8. pagingEnabled 按页滚动

    scrollView.pagingEnabled = YES;

    // 9. scrollEnabled 滚动视图能否滚动, 默认为YES, NO(不可以滚)

    scrollView.scrollEnabled = YES;

    // 10. showsHorizontalScrollIndicator 是否显示水平滚动指示器

    scrollView.showsHorizontalScrollIndicator = YES;

    // 11. showsVerticalScrollIndicator 是否显示垂直滚动的指示器

    scrollView.showsVerticalScrollIndicator = YES;

    // 12. 滚动指示器的边距

    scrollView.scrollIndicatorInsets = UIEdgeInsetsMake(, , , );

    // 13. indicatorStyle 滚动指示器的颜色(深色背景丶浅色背景)

    scrollView.indicatorStyle = UIScrollViewIndicatorStyleBlack;

    // 14.

    // scrollView.tracking 用户有没有开始拖动

    // scrollView.tracking

    // scrollView.dragging 用户是否正在拖动

    // scrollView.dragging

    // scrollView.decelerating 是否减速中

    // scrollView.decelerating

    // 14. scrollsToTop 滚动视图, 双击状态栏手势是否存在

    scrollView.scrollsToTop = NO;

    // 15. 代理

    scrollView.delegate = self;

    // 16. 键盘消失模式(一般用这个UIScrollViewKeyboardDismissModeOnDrag)

    scrollView.keyboardDismissMode = UIScrollViewKeyboardDismissModeOnDrag;

    // 测试:

    UITextField *textField = [[UITextField alloc] initWithFrame:CGRectMake(, , kScreenWidth - , )];

    textField.backgroundColor = [UIColor cyanColor];

    [scrollView addSubview:textField];

    // 17. 缩放系数

    // 如果想进行视图放大缩小, 必须实现viewForZoomingInScrollview:

    scrollView.minimumZoomScale = ;

    scrollView.maximumZoomScale = ;

}

// 与其想要缩放的子视图绑定, scrollView的contentSize会跟随这个子视图改变

- (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView {

    return scrollView.subviews.firstObject;

}

// 滚动视图滚动, 就会执行

- (void)scrollViewDidScroll:(UIScrollView *)scrollView {

    // tracking 用户触摸

    if (scrollView.tracking) {

        NSLog(@"正在拖动滚动");

    } else {

          NSLog(@"自己滚动中");

    }

    // dragging 用户开始滑动

    if (scrollView.dragging) {

        NSLog(@"");

    }

    // decelerating 用户触摸结束

    if (scrollView.decelerating) {

        NSLog(@"");

    }

}

// 将要开始拖拽

- (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView {

   // NSLog(@"开始拖拽");

}

// 将要结束拖拽

- (void)scrollViewWillEndDragging:(UIScrollView *)scrollView withVelocity:(CGPoint)velocity targetContentOffset:(inout CGPoint *)targetContentOffset {

}

// 将要开始进行减速

- (void)scrollViewWillBeginDecelerating:(UIScrollView *)scrollView {

   // NSLog(@"开始减速");

}

// 已经结束减速

- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView {

    //NSLog(@"结束减速");

}

- (void)didReceiveMemoryWarning {

    [super didReceiveMemoryWarning];

    // Dispose of any resources that can be recreated.

}