IOS开发之UIScrollView实现图片轮播器的无限滚动

// .h//// ESPicPageView.h// 享技//// Created by 11 on 11/30/15.// Copyright © 2015 soulghost. All rights reserved.//#import <UIKit/UIKit.h>@interface ESPicPageView : UIView@property (nonatomic, strong) NSArray *images;@end// --------------------------------------------// .m//// ESPicPageView.m// 享技//// Created by 11 on 11/30/15.// Copyright © 2015 soulghost. All rights reserved.//#import "ESPicPageView.h"#import "UIImageView+WebCache.h"@interface ESPicPageView () <UIScrollViewDelegate>@property (nonatomic, weak) UIScrollView *scrollView;@property (nonatomic, weak) UIPageControl *pageControl;@property (nonatomic, assign) CGFloat imgW;@property (nonatomic, assign) CGFloat imgH;@property (nonatomic, strong) NSTimer *timer;@property (nonatomic, strong) NSArray *imageViews;@property (nonatomic, assign) NSInteger imageCount;@end@implementation ESPicPageView- (instancetype)initWithFrame:(CGRect)frame{  if (self = [super initWithFrame:frame]) {    self.backgroundColor = [UIColor blueColor];    UIScrollView *scrollView = [[UIScrollView alloc] init];    self.scrollView = scrollView;    self.scrollView.delegate = self;    self.scrollView.pagingEnabled = YES;    self.scrollView.showsHorizontalScrollIndicator = NO;    self.scrollView.backgroundColor = [UIColor whiteColor];    [self addSubview:scrollView];    self.imgW = frame.size.width;    self.imgH = frame.size.height;    [self setNeedsLayout];    UIPageControl *pageControl = [[UIPageControl alloc] initWithFrame:CGRectMake(frame.size.width - 50, frame.size.height - 10, 0, 0)];    self.pageControl = pageControl;    self.pageControl.numberOfPages = 1;    [self addSubview:pageControl];    self.timer = [NSTimer scheduledTimerWithTimeInterval:2.0 target:self selector:@selector(nextImage) userInfo:nil repeats:YES];    [[NSRunLoop currentRunLoop] addTimer:self.timer forMode:NSRunLoopCommonModes];  }  return self;}- (void)nextImage{  NSInteger page = self.pageControl.currentPage;  page = self.pageControl.currentPage + 1;  CGPoint offset = CGPointMake((1 + page) * self.imgW, 0);  [self.scrollView setContentOffset:offset animated:YES];}- (void)setupImageViews{  for (int i = 0; i < self.images.count + 2; i++) {    UIImageView *imageView = [[UIImageView alloc] init];    CGFloat imageX = i * self.imgW;    CGFloat imageY = 0;    CGFloat imageW = self.imgW;    CGFloat imageH = self.imgH;    imageView.frame = CGRectMake(imageX, imageY, imageW,imageH);    [self.scrollView insertSubview:imageView atIndex:0];  }}- (NSArray *)imageViews{  if (_imageViews == nil) {    NSMutableArray *arr = [NSMutableArray array];    for (int i = 0; i < self.images.count + 2; i++) {      UIImageView *imageView = [[UIImageView alloc] init];      CGFloat imageX = i * self.imgW;      CGFloat imageY = 0;      CGFloat imageW = self.imgW;      CGFloat imageH = self.imgH;      imageView.frame = CGRectMake(imageX, imageY, imageW,imageH);      [self.scrollView insertSubview:imageView atIndex:0];      [arr addObject:imageView];    }    _imageViews = arr;  }  return _imageViews;}- (void)setImages:(NSArray *)images{  _images = images;  self.imageCount = images.count;  self.pageControl.numberOfPages = self.imageCount;  [self addPics];}- (void)addPics{  for (int i = 0; i < self.images.count + 2; i++) {    UIImageView *imageView = self.imageViews[i];    if (i == 0) {      imageView.image = [self.images lastObject];    }else if(i == self.images.count + 1){      imageView.image = [self.images firstObject];    }else{      imageView.image = self.images[i - 1];    }  }}- (void)layoutSubviews{  [super layoutSubviews];  self.scrollView.frame = self.bounds;  self.scrollView.contentSize = CGSizeMake((self.imageCount + 2) * self.imgW, 0);  [self.scrollView setContentOffset:CGPointMake(self.imgW, 0) animated:NO];}- (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView{  [self.timer invalidate];  self.timer = nil;}- (void)scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate{  self.timer = [NSTimer scheduledTimerWithTimeInterval:2.0 target:self selector:@selector(nextImage) userInfo:nil repeats:YES];  [[NSRunLoop currentRunLoop ] addTimer:self.timer forMode:NSRunLoopCommonModes];}- (void)scrollViewDidScroll:(UIScrollView *)scrollView{  if (scrollView.contentOffset.x == self.imgW * (self.imageCount + 1)) {    [self.scrollView setContentOffset:CGPointMake(self.imgW, 0) animated:NO];  }else if(scrollView.contentOffset.x == 0){    [self.scrollView setContentOffset:CGPointMake(self.imgW * (self.imageCount), 0) animated:NO];  }  self.pageControl.currentPage = (self.scrollView.contentOffset.x + self.imgW * 0.5f) / self.imgW - 1;}@end