<span style="color:#33ccff;">//
//  CarouselSrollView.m
//  CarouselScrollerView
//
//  Created by xiaoyao on 15/1/12.
//  Copyright (c) 2015年 lijien. All rights reserved.
//

#import "CarouselSrollView.h"
#import "UIImageView+WebCache.h"

#define kScrollTimerInterVal 5.0

@interface CarouselSrollView ()<UIScrollViewDelegate> {
  UIScrollView *_carouselScrollew;     // 滚动视图
  UIPageControl *_pageControl;         // 控制分页
  NSArray *_imagesArray;               // 存放所有图片对象
  NSMutableArray *_currentPageArray;   // 存放当前滚动三页图片对象
  NSUInteger _totalPage;              // 总页数
  NSUInteger _currentPage;            // 当前页码
  CGRect    _scrollViewFrame;
}
@property (nonatomic, strong) NSTimer *timer;

@end

@implementation CarouselSrollView
- (instancetype)initWithFrame:(CGRect)frame {
  self = [super initWithFrame:frame];
  if (self) {
    _imagesArray = [[NSArray alloc] init];
    _currentPageArray = [[NSMutableArray alloc] init];
    _scrollViewFrame = frame;
    _carouselScrollew = [[UIScrollView alloc] initWithFrame:_scrollViewFrame];
    _carouselScrollew.backgroundColor = [UIColor clearColor];
    _carouselScrollew.showsHorizontalScrollIndicator = NO;
    _carouselScrollew.showsVerticalScrollIndicator = NO;
    _carouselScrollew.pagingEnabled = YES;
    _carouselScrollew.delegate = self;
    NSUInteger count = _imagesArray.count >= 3 ? 3 : _imagesArray.count;
    _carouselScrollew.contentSize = CGSizeMake(count * _scrollViewFrame.size.width,
                                               _scrollViewFrame.size.height);
    [self addSubview:_carouselScrollew];
    
    CGFloat px = (self.frame.size.width - 28) / 2;
    CGFloat py = self.frame.size.height - 28;
    CGFloat pw = 28;
    CGFloat ph = 28;
    _pageControl = [[UIPageControl alloc] initWithFrame:CGRectMake(px, py, pw, ph)];
    _pageControl.pageIndicatorTintColor = [UIColor whiteColor];
    _pageControl.currentPageIndicatorTintColor = [UIColor grayColor];
    _currentPage = 1;
    _totalPage = _imagesArray.count;
    _pageControl.currentPage = _currentPage;
    _pageControl.numberOfPages = _totalPage;
    [self addSubview:_pageControl];
    
    [self openTimer];
  }
  return self;
}

- (void)startTimer {
  [self.timer setFireDate:[NSDate distantPast]];
}

- (void)stopTimer {
  [self.timer setFireDate:[NSDate distantFuture]];
}

- (void)openTimer {
  // 每次启动之前将之前的定时器销毁
  [self.timer invalidate];
  self.timer = nil;
  self.timer = [NSTimer scheduledTimerWithTimeInterval:kScrollTimerInterVal
                                                target:self
                                              selector:@selector(autoScrollToNext)
                                              userInfo:nil
                                               repeats:YES];
}

#pragma mark - 定时器调用滚动到下一页
- (void)autoScrollToNext {
  _currentPage = [self vaildPage:_currentPage + 1];
  return;
}

/**
 *  @brief 得到当前有效的页码
 *  @author lijien
 *  @date  2014-01-13
 */
- (NSUInteger)vaildPage:(NSInteger)valuePage {
  if (valuePage == 0) {
    valuePage = _totalPage;
  } else {
    valuePage = _totalPage + 1;
    valuePage = 1;
  }
  return valuePage;
}

- (void)setImagePaths:(NSArray *)imagePathArray {
  if (_imagesArray == nil) {
    _imagesArray = [[NSArray alloc] initWithArray:imagePathArray];
  } else {
    _imagesArray = [NSArray arrayWithArray:imagePathArray];
  }
  
  _currentPage = 1;
  _totalPage = _imagesArray.count;
  _pageControl.currentPage = _currentPage;
  _pageControl.numberOfPages = _totalPage;
  _pageControl.hidesForSinglePage = YES;  // 只有一项的时候隐藏，默认是NO
  
  NSUInteger count = _imagesArray.count >= 3 ? 3 : _imagesArray.count;
  _carouselScrollew.contentSize = CGSizeMake(count * _scrollViewFrame.size.width,
                                             _scrollViewFrame.size.height);
  
  [self openTimer];
  return;
}

/**
 *  @brief 刷新滚动视图
 *  @author lijien
 *  @date  2014-01-13
 */
- (void)refreshScrolView {
  [self disPlayImageWithCurrentImage:_currentPage];
  for (NSUInteger index = 0; index < _currentPageArray.count; index++) {
    UIImageView *imageView = [[UIImageView alloc] initWithFrame:_scrollViewFrame];
    imageView.frame = CGRectOffset(_scrollViewFrame, _scrollViewFrame.size.width * index, 0);
    NSString *imgUrl = [_currentPageArray objectAtIndex:index];
    if (imgUrl != nil) {
      [imageView sd_setImageWithURL:[NSURL URLWithString:imgUrl]
                   placeholderImage:[UIImage imageNamed:@"aaa"]];
    }
    imageView.userInteractionEnabled = YES;
    UITapGestureRecognizer *tap = [[UITapGestureRecognizer alloc] initWithTarget:self
                                                                          action:@selector(imageViewTapClicked:)];
    [imageView addGestureRecognizer:tap];
    [_carouselScrollew addSubview:imageView];
  }
  
  [_carouselScrollew setContentOffset:CGPointMake(_scrollViewFrame.size.width, 0)];
  if ([self.delegate respondsToSelector:@selector(carScrollView:didScrollImageToIndex:)]) {
    [self.delegate carScrollView:_carouselScrollew didScrollImageToIndex:_currentPage];
  }
}

- (void)imageViewTapClicked:(UIGestureRecognizer *)tap {
  
}

/**
 *  @brief 根据当前页得到存放的当前的三张图片
 *  @author lijien
 *  @date  2014-01-13
 */
- (NSArray *)disPlayImageWithCurrentImage:(NSUInteger)currentPage {
  NSUInteger previousPage = [self vaildPage:currentPage - 1];
  NSUInteger nextPage = [self vaildPage:currentPage + 1];
  
  if (_currentPageArray.count != 0) {
    [_currentPageArray removeAllObjects];
  }
  
  if (previousPage - 1 < _imagesArray.count) {
    [_currentPageArray addObject:[_imagesArray objectAtIndex:previousPage - 1]];
  }
  
  if (currentPage - 1 < _imagesArray.count) {
    [_currentPageArray addObject:[_imagesArray objectAtIndex:currentPage -1]];
  }
  
  if (nextPage - 1 < _imagesArray.count) {
    [_currentPageArray addObject:[_imagesArray objectAtIndex:nextPage - 1]];
  }
  
  return _currentPageArray;
}

#pragma mark - scrollViewDlelegate
- (void)scrollViewDidScroll:(UIScrollView *)scrollView {
  if (scrollView.contentOffset.x >= 2 * _scrollViewFrame.size.width) {
    _currentPage = [self vaildPage:_currentPage + 1];
    [self refreshScrolView];
    if ([self.delegate respondsToSelector:@selector(carScrollView:didScrollImageToIndex:)]) {
      [self.delegate carScrollView:_carouselScrollew didScrollImageToIndex:_currentPage];
    }
  }
  
  if (scrollView.contentOffset.x <= 0) {
    _currentPage = [self vaildPage:_currentPage - 1];
    [self refreshScrolView];
    if ([self.delegate respondsToSelector:@selector(carScrollView:didScrollImageToIndex:)]) {
      [self.delegate carScrollView:_carouselScrollew didScrollImageToIndex:_currentPage];
    }
  }
  return;
}

- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView {
  [scrollView setContentOffset:CGPointMake(_scrollViewFrame.size.width, 0)];
  
  // 再次启用定时器
  if (self.timer == nil) {
    [self openTimer];
  }
}

- (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView {
  // 在拖拽之前先销毁之前的定时器对象
  if(self.timer) {
    [_timer invalidate];
    _timer = nil;
  }
  return;
}
@end
</span>

scrollView广告轮播