UIScrollView, 滚动视图

 UIScrollView, 滚动视图

    UIScrollView, 滚动视图, 继承于UIView, 用于显示超过一个屏幕的内容

    frame: 是滚动视图可视区域的大小

    UIScrollView *scrollView = [[UIScrollView alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
    scrollView.backgroundColor = [UIColor colorWithRed:0.586 green:1.000 blue:0.977 alpha:1.000];

    内容页的大小, 默认值:CGSizeZero

    contentSize.width > frame. 水平滚动

    contentSize.height > frame.height: 垂直滚动

 scrollView.contentSize = CGSizeMake(375 * 2, 667 * 2); 

   是否能滚动到顶部(点击状态栏触发), 默认是YES
    scrollView.scrollsToTop = YES;
    内容页的偏移量
    scrollView.contentOffset = CGPointMake(0, 0);
    [scrollView setContentOffset:CGPointMake(0, 0) animated:YES];
    是否可以滚动, 默认YES
    scrollView.scrollEnabled = YES;
    是否显示垂直滚动条, 默认是YES
    scrollView.showsVerticalScrollIndicator = YES;
    是否显示水平滚动条, 默认是YES
    scrollView.showsHorizontalScrollIndicator = YES;
    是否回弹(前提: 能够滚动), 默认YES
    scrollView.bounces = YES;
    是否回弹(前提: 不能滚动, bounces是YES), 默认NO
    scrollView.alwaysBounceVertical = YES;
    scrollView.alwaysBounceHorizontal = YES;
    是否整屏滚动, 默认是NO
    scrollView.pagingEnabled = NO;
    代理
    scrollView.delegate = self;
    scrollView.tag = 1024;
    [self.view addSubview:scrollView];
    [scrollView release];

UIImageView如果不设置frame, frame大小 = 图片大小

  imageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"Baymax.jpg"]]; 

只有添加到scrollView上, 视图才能跟着scrollView一起滚动

    [scrollView addSubview:imageView];
    [imageView release];

 滚动视图上的内容缩放

    1.设置delegate

    2.修改scrollView属性

   当前的缩放比例, 默认值1.0
    scrollView.zoomScale = 1.0;
    最大缩放比例, 默认为1.0
    scrollView.maximumZoomScale = 4.0;
    最小缩放比例, 默认为1.0
    scrollView.minimumZoomScale = 0.5;

 3.指定缩放的视图

    UIPageControl, 页面控件, 继承于UIControl, 一般配合UIScrollView使用

    注: UIPageControl适用于页数比较少的情况, 比如5页以内; 如果页数比较多, 可以使用UILabel直接显示"第99页"

   UIPageControl *pageControl = [[UIPageControl alloc] initWithFrame:CGRectMake(100, 600, 175, 40)];
    pageControl.backgroundColor = [UIColor blackColor];
    设置页数, 默认为0
    pageControl.numberOfPages = 5;
    当前页数, 默认为0
    pageControl.currentPage = 1;
    未选中圆点颜色
    pageControl.pageIndicatorTintColor = [UIColor redColor];
    选中圆点颜色
    pageControl.currentPageIndicatorTintColor = [UIColor greenColor];
    当只有一页时, 是否隐藏
    pageControl.hidesForSinglePage = YES;
    [pageControl addTarget:self action:@selector(changePage:) forControlEvents:UIControlEventValueChanged];
    [self.view addSubview:pageControl];
    [pageControl release];

    
    UIButton *nextButton = [UIButton buttonWithType:UIButtonTypeSystem];
    nextButton.frame = CGRectMake(375 - 100, 40, 80, 30);
    [nextButton setTitle:@"下 一 页" forState:UIControlStateNormal];
    [nextButton setTitleColor:[UIColor whiteColor] forState:UIControlStateNormal];
    [nextButton addTarget:self action:@selector(nextPage) forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:nextButton];
    
    UIButton *reset = [UIButton buttonWithType:UIButtonTypeSystem];
    reset.frame = CGRectMake(20, 40, 80, 30);
    [reset setTitle:@"还    原" forState:UIControlStateNormal];
    [reset setTitleColor:[UIColor whiteColor] forState:UIControlStateNormal];
    [reset addTarget:self action:@selector(reset) forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:reset];

- (void)nextPage {
    UIScrollView *scrollView = (UIScrollView *)[self.view viewWithTag:1024];
    改变偏移量
//  scrollView.contentOffset = CGPointMake(375, 0);
    [scrollView setContentOffset:CGPointMake(375, 0) animated:YES];
    
}

- (void)reset {
    UIScrollView *scrollView = (UIScrollView *)[self.view viewWithTag:1024];
    重置scrollView的缩放比例
//    scrollView.zoomScale = 1.0;
    [scrollView setZoomScale:1.0 animated:YES];
}

#pragma mark - UIScrollViewDelegate
//当滚动视图的偏移量做改变, 执行这个方法
- (void)scrollViewDidScroll:(UIScrollView *)scrollView {
    NSLog(@"已经滚动");
}

- (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView {
    NSLog(@"将要开始拖拽");
}

- (void)scrollViewWillEndDragging:(UIScrollView *)scrollView withVelocity:(CGPoint)velocity targetContentOffset:(inout CGPoint *)targetContentOffset {
    //inout: 方法 内部使用的变量 和 外部使用的变量 是同一个
    NSLog(@"将要结束拖拽");
}

- (void)scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate {
    NSLog(@"已经结束拖拽");
}

- (void)scrollViewWillBeginDecelerating:(UIScrollView *)scrollView {
    NSLog(@"将要开始减速");
}

- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView {
    NSLog(@"已经结束减速");
}

//调用setContentOffset:animated:这个方法触发
- (void)scrollViewDidEndScrollingAnimation:(UIScrollView *)scrollView {
     NSLog(@"已经结束滚动动画");
}

- (BOOL)scrollViewShouldScrollToTop:(UIScrollView *)scrollView {
    return YES;
}

- (void)scrollViewDidScrollToTop:(UIScrollView *)scrollView {
    NSLog(@"已经滚动到顶部");
}

- (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView {
    //指定缩放的视图
    return imageView;
}

- (void)scrollViewDidZoom:(UIScrollView *)scrollView {
    NSLog(@"滚动视图已经缩放");
}

- (void)scrollViewWillBeginZooming:(UIScrollView *)scrollView withView:(UIView *)view {
    NSLog(@"滚动视图将要开始缩放");
}

- (void)scrollViewDidEndZooming:(UIScrollView *)scrollView withView:(UIView *)view atScale:(CGFloat)scale {

    NSLog(@"滚动视图已经结束缩放");

} 

#import "WelcomeViewController.h"
@interface WelcomeViewController () <UIScrollViewDelegate> {
    UIScrollView *bgScrollView;
    UIPageControl *pagecontrol;
}
@end
@implementation WelcomeViewController
- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view.
    
    //创建滚动视图
    bgScrollView = [[UIScrollView alloc] initWithFrame:self.view.frame];
    bgScrollView.backgroundColor = [UIColor colorWithRed:0.966 green:1.000 blue:0.429 alpha:1.000];
    bgScrollView.contentSize = CGSizeMake(320 * 4, 568);
    bgScrollView.pagingEnabled = YES;
    bgScrollView.showsHorizontalScrollIndicator = NO;
    bgScrollView.tag = 101;
    bgScrollView.delegate = self;
    [self.view addSubview:bgScrollView];
    [bgScrollView release];
    
    for (NSInteger i = 1; i <= 4 ; i++) {
        NSString *name = [NSString stringWithFormat:@"%ld.jpg", i];
        UIImageView *imageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:name]];
        imageView.frame = CGRectMake(320 * (i - 1), 0, 320, 568);
        [bgScrollView addSubview:imageView];
    }
    pagecontrol = [[UIPageControl alloc] initWithFrame:CGRectMake(0, 528, 320, 40)];
//  pagecontrol.backgroundColor = [UIColor yellowColor];
    pagecontrol.numberOfPages = 4;
    pagecontrol.pageIndicatorTintColor = [UIColor grayColor];
    pagecontrol.currentPageIndicatorTintColor = [UIColor greenColor];
    [pagecontrol addTarget:self action:@selector(changePage:) forControlEvents:UIControlEventValueChanged];
    [self.view addSubview:pagecontrol];
    [pagecontrol release];
}
- (void)changePage:(UIPageControl *)pageControl {
    bgScrollView.contentOffset = CGPointMake(320 * pageControl.currentPage, 0);
}
- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}
#pragma mark - UIScrollViewDelegate
- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView
{
    pagecontrol.currentPage = scrollView.contentOffset.x / 320;
    NSLog(@"%.2lf", scrollView.contentOffset.x / 320);
}
@end