IOS第六天(3:scrollView 图片轮播器)

IOS第六天(3:scrollView 图片轮播器)

#import "HMViewController.h"

#define kImageCount     5

@interface HMViewController () <UIScrollViewDelegate>

@property (nonatomic, strong) UIScrollView *scrollView;

@property (nonatomic, strong) UIPageControl *pageControl;

@property (nonatomic, strong) NSTimer *timer;

@end

@implementation HMViewController

- (UIScrollView *)scrollView

{

    if (_scrollView == nil) {

        _scrollView = [[UIScrollView alloc] initWithFrame:CGRectMake(, , , )];

        _scrollView.backgroundColor = [UIColor redColor];

        [self.view addSubview:_scrollView];

        // 取消弹簧效果

        _scrollView.bounces = NO;

        // 取消水平滚动条

        _scrollView.showsHorizontalScrollIndicator = NO;

        _scrollView.showsVerticalScrollIndicator = NO;

        // 要分页

        _scrollView.pagingEnabled = YES;

        // contentSize

        _scrollView.contentSize = CGSizeMake(kImageCount * _scrollView.bounds.size.width, );

        // 设置代理

        _scrollView.delegate = self;

    }

    return _scrollView;

}

- (UIPageControl *)pageControl

{

    if (_pageControl == nil) {

        // 分页控件，本质上和scrollView没有任何关系，是两个独立的控件

        _pageControl = [[UIPageControl alloc] init];

        // 总页数

        _pageControl.numberOfPages = kImageCount;

        // 控件尺寸

        CGSize size = [_pageControl sizeForNumberOfPages:kImageCount];

        _pageControl.bounds = CGRectMake(, , size.width, size.height);

        _pageControl.center = CGPointMake(self.view.center.x, );

        // 设置颜色

        _pageControl.pageIndicatorTintColor = [UIColor redColor];

        _pageControl.currentPageIndicatorTintColor = [UIColor blackColor];

        [self.view addSubview:_pageControl];

        // 添加监听方法

        /** 在OC中，绝大多数"控件"，都可以监听UIControlEventValueChanged事件，button除外" */

        [_pageControl addTarget:self action:@selector(pageChanged:) forControlEvents:UIControlEventValueChanged];

    }

    return _pageControl;

}

// 分页控件的监听方法

- (void)pageChanged:(UIPageControl *)page

{

    NSLog(@"%d", page.currentPage);

    // 根据页数，调整滚动视图中的图片位置 contentOffset

    CGFloat x = page.currentPage * self.scrollView.bounds.size.width;

    [self.scrollView setContentOffset:CGPointMake(x, ) animated:YES];

}

// 视图加载完成调用，通常用来设置数据

- (void)viewDidLoad

{

    [super viewDidLoad];

    // 设置图片

    for (int i = ; i < kImageCount; i++) {

        NSString *imageName = [NSString stringWithFormat:@"img_%02d", i + ];

        UIImage *image = [UIImage imageNamed:imageName];

        UIImageView *imageView = [[UIImageView alloc] initWithFrame:self.scrollView.bounds];

        imageView.image = image;

        [self.scrollView addSubview:imageView];

    }

    // 计算imageView的位置

    [self.scrollView.subviews enumerateObjectsUsingBlock:^(UIImageView *imageView, NSUInteger idx, BOOL *stop) {

        // 调整x => origin => frame

        CGRect frame = imageView.frame;

        frame.origin.x = idx * frame.size.width;

        imageView.frame = frame;

    }];

//    NSLog(@"%@", self.scrollView.subviews);

    // 分页初始页数为0

    self.pageControl.currentPage = ;

    // 启动时钟

    [self startTimer];

}

- (void)startTimer

{

    self.timer = [NSTimer timerWithTimeInterval:2.0 target:self selector:@selector(updateTimer) userInfo:nil repeats:YES];

    // 添加到运行循环

    [[NSRunLoop currentRunLoop] addTimer:self.timer forMode:NSRunLoopCommonModes];

}

- (void)updateTimer

{

    // 页号发生变化

    // (当前的页数 + 1) % 总页数

    int page = (self.pageControl.currentPage + ) % kImageCount;

    self.pageControl.currentPage = page;

    NSLog(@"%d", self.pageControl.currentPage);

    // 调用监听方法，让滚动视图滚动

    [self pageChanged:self.pageControl];

}

#pragma mark - ScrollView的代理方法

// 滚动视图停下来，修改页面控件的小点（页数）

- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView

{

    // 停下来的当前页数

    NSLog(@"%@", NSStringFromCGPoint(scrollView.contentOffset));

    // 计算页数

    int page = scrollView.contentOffset.x / scrollView.bounds.size.width;

    self.pageControl.currentPage = page;

}

/**

 修改时钟所在的运行循环的模式后，抓不住图片

 解决方法：抓住图片时，停止时钟，送售后，开启时钟

 */

- (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView

{

    NSLog(@"%s", __func__);

    // 停止时钟，停止之后就不能再使用，如果要启用时钟，需要重新实例化

    [self.timer invalidate];

}

- (void)scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate

{

    NSLog(@"%s", __func__);

    [self startTimer];

}

@end