iOS图片轮播

//
//  UYViewController.m
//  图片轮播器
//
//  Created by jiangys on 15/5/23.
//  Copyright (c) 2015年 uxiaoyuan. All rights reserved.
//

#import "UYViewController.h"
#define kImageCount 5

@interface UYViewController ()<UIScrollViewDelegate>

@property (nonatomic,strong) UIScrollView *scrollView;
@property (nonatomic,strong) UIPageControl *pageControl;

@property (nonatomic, strong) NSTimer *timer;

@end

@implementation UYViewController

-(UIScrollView *)scrollView
{
    if (_scrollView==nil) {
        //如果为空，创建一个
        _scrollView=[[UIScrollView alloc] initWithFrame:CGRectMake(10, 20, 300, 130)];
        _scrollView.backgroundColor=[UIColor redColor];
        
        //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, 0);
        
        // 设置代理
        _scrollView.delegate = self;
        
        [self.view addSubview:_scrollView];
                     
    }
    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(0, 0, size.width, size.height);
        _pageControl.center = CGPointMake(self.view.center.x, 130);
        
        // 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
{
    // 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, 0) animated:YES];
}

- (void)viewDidLoad
{
    [super viewDidLoad];
	//设置图片
    for (int i=0; i<kImageCount; i++) {
        NSString *imageName=[NSString stringWithFormat:@"img_%02d",i+1];
        UIImage *image=[UIImage imageNamed:imageName];
        
        UIImageView *imageView=[[UIImageView alloc] initWithFrame:self.scrollView.bounds];
        imageView.image=image;
        
        [self.scrollView addSubview:imageView];
    }
    //计算imageView
    [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;
    }];
    
    // 分页初始页数为0
    self.pageControl.currentPage = 0;
    
    // 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 + 1) % kImageCount;
    self.pageControl.currentPage = page;

    // 调用监听方法，让滚动视图滚动
    [self pageChanged:self.pageControl];
}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.s
    
}



#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
{
    // 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
{
    // 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
{
    [self startTimer];
}


@end