iOS广告Banner，使用三个ImgView无限循环轮播

图片加载使用 SDWebImage 第三方库。

WTCycleRollView.h

#import <UIKit/UIKit.h>@interface WTCycleRollView : UIView@property (nonatomic, assign) NSTimeInterval rollTimeInterval;/** 返回 WTCycleRollView 对象 @param frame 位置尺寸 @return WTCycleRollView 对象 */+ (instancetype)cycleRollViewWithFrame:(CGRect)frame;/** 设置图片源、是否自动滚动、点击图片的回调 @param imgUrls 图片源 @param autoCycleRoll 是否自动滚动 @param clickImgBlock 点击图片的回调 */- (void)setImgUrls:(NSArray *)imgUrls autoCycleRoll:(BOOL)autoCycleRoll clickImgBlock:(void(^)(NSInteger selectedIndex))clickImgBlock;/** 暂停自动滚动 */- (void)pauseCycleRoll;/** 开始自动滚动【在暂停的状态下】 */- (void)startCycleRoll;@end

WTCycleRollView.m

#import "WTCycleRollView.h"#import "UIImageView+WebCache.h"typedef void(^ClickImgBlock) (NSInteger);@interface WTCycleRollView () <UIScrollViewDelegate>@property (nonatomic, strong) UIScrollView *scrollView;@property (nonatomic, strong) UIPageControl *pageControl;@property (nonatomic, strong) UIImageView *leftImgView;@property (nonatomic, strong) UIImageView *middleImgView;@property (nonatomic, strong) UIImageView *rightImgView;/** 图片源 */@property (nonatomic, strong) NSArray *imgUrls;/** 当前显示的图片的 Index */@property (nonatomic, assign) NSInteger showIndex;/** 点击图片的回调 Block */@property (nonatomic, strong) ClickImgBlock clickImgBlock;/** 自动滚动的计时器 */@property (nonatomic, strong) NSTimer *cycleRollTimer;/** 是否手动滑动 */@property (nonatomic, assign) BOOL manual;@end@implementation WTCycleRollView/** 默认循环滚动的时间间隔(s) */static NSTimeInterval const DefaultRollTimeInterval = 4;#pragma mark - 懒加载- (UIImageView *)leftImgView {    if (!_leftImgView) {        _leftImgView = [[UIImageView alloc] initWithFrame:self.bounds];    }    return _leftImgView;}- (UIImageView *)middleImgView {    if (!_middleImgView) {        _middleImgView = [[UIImageView alloc] initWithFrame:CGRectMake(CGRectGetWidth(self.bounds), 0, CGRectGetWidth(self.bounds), CGRectGetHeight(self.bounds))];        /** 为中间正在显示的 ImgView 添加点击事件 */        UITapGestureRecognizer *tapGr = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(clickImgView)];        [_middleImgView setUserInteractionEnabled:YES];        [_middleImgView addGestureRecognizer:tapGr];    }    return _middleImgView;}- (UIImageView *)rightImgView {    if (!_rightImgView) {        _rightImgView = [[UIImageView alloc] initWithFrame:CGRectMake(CGRectGetWidth(self.bounds) * 2, 0, CGRectGetWidth(self.bounds), CGRectGetHeight(self.bounds))];    }    return _rightImgView;}- (UIScrollView *)scrollView {    if (!_scrollView) {        _scrollView = [[UIScrollView alloc] initWithFrame:self.bounds];        _scrollView.delegate = self;        _scrollView.showsHorizontalScrollIndicator = NO;        _scrollView.pagingEnabled = YES;    }    return _scrollView;}- (UIPageControl *)pageControl {    if (!_pageControl) {        _pageControl = [[UIPageControl alloc] initWithFrame:CGRectMake(0, CGRectGetHeight(self.bounds) - 20, CGRectGetWidth(self.bounds), 20)];        _pageControl.layer.shadowOpacity = 0.3;        _pageControl.layer.shadowOffset = CGSizeMake(0, 0);    }    return _pageControl;}#pragma mark - 初始化- (instancetype)initWithFrame:(CGRect)frame {    if (self = [super initWithFrame:frame]) {        [self addSubview:self.scrollView];        [_scrollView addSubview:self.leftImgView];        [_scrollView addSubview:self.middleImgView];        [_scrollView addSubview:self.rightImgView];        [self addSubview:self.pageControl];    }    return self;}#pragma mark - 类方法 返回 WTCycleRollView+ (instancetype)cycleRollViewWithFrame:(CGRect)frame {    return [[self alloc] initWithFrame:frame];}#pragma mark - 设置图片显示，自动滚动- (void)setImgUrls:(NSArray *)imgUrls autoCycleRoll:(BOOL)autoCycleRoll clickImgBlock:(void (^)(NSInteger))clickImgBlock {    _clickImgBlock = clickImgBlock;    _imgUrls = imgUrls;    _pageControl.numberOfPages = [imgUrls count];    _pageControl.currentPage = 0;    if ([_imgUrls count] > 1) {        [_leftImgView sd_setImageWithURL:[NSURL URLWithString:[imgUrls lastObject]]];        [_middleImgView sd_setImageWithURL:[NSURL URLWithString:[imgUrls firstObject]]];        [_rightImgView sd_setImageWithURL:[NSURL URLWithString:[imgUrls objectAtIndex:1]]];        _scrollView.contentSize = CGSizeMake(CGRectGetWidth(self.bounds) * 3, 0);        [_scrollView setContentOffset:CGPointMake(CGRectGetWidth(self.bounds), 0)];        if (autoCycleRoll) {            [self stopTimer];            _cycleRollTimer = [NSTimer scheduledTimerWithTimeInterval:DefaultRollTimeInterval target:self selector:@selector(cycleRoll) userInfo:nil repeats:YES];        } else {            [self stopTimer];        }    } else {        _scrollView.contentSize = CGSizeMake(CGRectGetWidth(self.bounds), 0);        [_leftImgView removeFromSuperview];        [_rightImgView removeFromSuperview];        if ([imgUrls count]) {            [_middleImgView sd_setImageWithURL:[NSURL URLWithString:[imgUrls firstObject]]];            _middleImgView.frame = self.bounds;        }    }}#pragma mark - 自动滚动的事件- (void)cycleRoll {    // 当手动滚动的时候，跳过此次循环    if (_manual) {        _manual = NO;    } else {        [_scrollView setContentOffset:CGPointMake(CGRectGetWidth(self.bounds) * 2, 0) animated:YES];    }}- (void)clickImgView {    !_clickImgBlock ? : _clickImgBlock(_showIndex);}#pragma mark - UIScrollView Delegate/** ScrollView 滑动减速停止回调【这里根据 ScrollView 的偏移量来判断是向左滑还是向右滑】 */- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView {    if ([_imgUrls count]) {        CGFloat offsetX = scrollView.contentOffset.x;        if (offsetX <= 0) {            // 向右滑，即将显示上一张图片(若当前显示的是第一张，则上一张为最后一张)            self.showIndex = (_showIndex + [_imgUrls count] - 1) % [_imgUrls count];        } else if (offsetX >= CGRectGetWidth(self.bounds) * 2) {            // 向右滑，即将显示下一张图片(若当前显示的是最后一张，则下一张为第一张)            self.showIndex = (_showIndex + 1) % [_imgUrls count];        }    }}/** 自动滑动【即代码设置的滚动(setContentOffset:animated:)】,不会直接调用上述方法(滑动减速停止回调),但会调用此方法,在此方法再调用上述方法便可 */- (void)scrollViewDidEndScrollingAnimation:(UIScrollView *)scrollView {    [self scrollViewDidEndDecelerating:_scrollView];}/** 手动滑动手指触摸屏幕的回调，暂停计时器 */- (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView {    [self pauseCycleRoll];}/** 手动滑动手指离开屏幕的回调，开启计时器 */- (void)scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate {    _manual = YES;  // 这里开启计时器会立即调用循环滚动的方法，用户体验不好，所以设置此参数，让其跳过这次循环滚动事件    [self startCycleRoll];}/** 根据 ScrollView 偏移量设置 PageControl 的当前页 */- (void)scrollViewDidScroll:(UIScrollView *)scrollView {    if ([_imgUrls count]) {        CGFloat offsetX = scrollView.contentOffset.x;        if (offsetX <= CGRectGetWidth(self.bounds) * 0.5) {            _pageControl.currentPage = (_showIndex + [_imgUrls count] - 1) % [_imgUrls count];        } else if (offsetX >= CGRectGetWidth(self.bounds) * 1.5) {            _pageControl.currentPage = (_showIndex + 1) % [_imgUrls count];        } else {            _pageControl.currentPage = _showIndex;        }    }}#pragma mark - 设置当前显示的图片- (void)setShowIndex:(NSInteger)showIndex {    _showIndex = showIndex;    // 不管向左滑还是向右滑，这里立即将将要显示的图片展示在中间的 ImgView 上，然后马上将 ScrollView 偏移量设置到显示中间的 ImgView    // 由于代码执行及屏幕显示渲染非常快，肉眼几乎看不出，所以这样就达到了效果    [_leftImgView sd_setImageWithURL:[NSURL URLWithString:_imgUrls[(_showIndex + [_imgUrls count] - 1) % [_imgUrls count]]]];    [_middleImgView sd_setImageWithURL:[NSURL URLWithString:_imgUrls[showIndex]]];    [_rightImgView sd_setImageWithURL:[NSURL URLWithString:_imgUrls[(showIndex + 1) % [_imgUrls count]]]];    // 切记，这里设置 ScrollView 偏移量不能用动画    [_scrollView setContentOffset:CGPointMake(CGRectGetWidth(self.bounds), 0)];}#pragma mark - 自动滚动时，计时器的暂停与启动/** 暂停计时器 */- (void)pauseCycleRoll {    if (_cycleRollTimer) {        [_cycleRollTimer setFireDate:[NSDate distantFuture]];    }}/** 启动定时器【在计时器暂停状态下】 */- (void)startCycleRoll {    if (_cycleRollTimer) {        [_cycleRollTimer setFireDate:[NSDate distantPast]];    }}#pragma mark - 停止计时器，并释放- (void)stopTimer {    if (_cycleRollTimer) {        [_cycleRollTimer invalidate];        _cycleRollTimer = nil;    }}#pragma mark - WTCycleRollView 释放的时候 停止计时器，并释放，否则会造成内存泄漏- (void)dealloc {    [self stopTimer];}@end