在iOS开发中，经常会在APP首页看到多张图片进行轮换。刚开始做的时候，感觉很麻烦，不是很好做，查阅资料后，我总结了一下，自己封装了一个简单的轮转图片库；
UIScrollView无限滑动 ,只需要三个View,左视图，中视图，右视图。无论向左滑动，还是向右滑动，都显示中间的一个View；
( _scrollView.contentOffset =CGPointMake(scrollView.bounds.size.width,0); )
// CircleScrollView.h
#import <UIKit/UIKit.h> #import "UIImageView+WebCache.h" // 当使用网络图片的时候，才会用到SDWebImage @protocol CircleScrollViewDelegate <NSObject> @optional /** * 滚动图片总数 * @return 要滚动的图片的个数 */ - (NSInteger) numberOfImagesInScrollView; /** * 返回索引位置的图片，仅当滚动的为图片时使用 * @param index 索引位置 * @return 索引位置的图片 */ -(UIImage *)imageForIndex:(NSInteger) index; /** * 返回索引位置的图片URL，仅当滚动的为图片时使用 * @param index 索引位置 * @return 索引位置对应的图片URL */ -(NSURL *)imageURLForIndex:(NSInteger)index; /** * 选中相应的视图的操作 * @param index 选中的相应的视图 */ - (void)didSelectAtIndex:(NSInteger) index; @end @interface CircleScrollView :UIView <UIScrollViewDelegate> @property (nonatomic,strong,readonly)UIScrollView *scrollView; @property (nonatomic,strong,readonly)UIPageControl *pageControl; @property (nonatomic,strong,readonly)UIImageView *leftView; @property (nonatomic,strong,readonly)UIImageView *middleView; @property (nonatomic,strong,readonly)UIImageView *rightView; @property (nonatomic,assign)int currentPageNo; @property (nonatomic,assign,getter=isAutoLoop)BOOL autoLoop;//是否自动轮动 //@property (nonatomic,copy) NSArray *scrollImgs; @property (nonatomic,weak)id<CircleScrollViewDelegate> delegate;//代理 @end
// CircleScrollView.m
#import "CircleScrollView.h"
@interfaceCircleScrollView ()
{
NSTimer *_timer;
}
@end
@implementation CircleScrollView
/*
自定义的ScrollView。功能如下：
循环滑动
使用分两步：
（1）创建数据源(数据源中存放要滚动的图片)
（2）_circleScrollView = [[CircleScrollView alloc] initWithFrame:CGRectMake(20, 20, 128, 128)];
（3）设置代理 _circleScrollView.delegate = self;
*/
-(instancetype)initWithFrame:(CGRect)frame{
self = [superinitWithFrame:frame];
if (self) {
_scrollView = [[UIScrollViewalloc]initWithFrame:self.bounds];
_scrollView.delegate =self;
_scrollView.showsHorizontalScrollIndicator =NO;
_pageControl = [[UIPageControlalloc]initWithFrame:CGRectMake(0,self.frame.size.height-10,self.frame.size.width,10)];
_pageControl.backgroundColor = [UIColorlightGrayColor];
_pageControl.pageIndicatorTintColor = [UIColorredColor];
_pageControl.currentPageIndicatorTintColor = [UIColorblueColor];
_pageControl.alpha =0.5;
_leftView = [[UIImageViewalloc]initWithFrame:CGRectMake(self.frame.size.width*0,0,self.frame.size.width,self.frame.size.height)];
_middleView = [[UIImageViewalloc]initWithFrame:CGRectMake(self.frame.size.width*1,0,self.frame.size.width,self.frame.size.height)];
_rightView = [[UIImageViewalloc]initWithFrame:CGRectMake(self.frame.size.width*2,0,self.frame.size.width,self.frame.size.height)];
[_scrollViewaddSubview:_leftView];
[_scrollViewaddSubview:_middleView];
[_scrollViewaddSubview:_rightView];
_scrollView.pagingEnabled =YES;
_scrollView.contentSize =CGSizeMake(self.frame.size.width*3,self.frame.size.height);
_scrollView.contentOffset =CGPointMake(self.frame.size.width,0);
[selfaddSubview:_scrollView];
[selfaddSubview:_pageControl];
}
returnself;
}
-(void)setDelegate:(id<CircleScrollViewDelegate>)delegate
{
// NSLog(@"设置代理");
_delegate = delegate;
if ([_delegaterespondsToSelector:@selector(numberOfImagesInScrollView)]) {
NSInteger number = [_delegatenumberOfImagesInScrollView];
_pageControl.numberOfPages = number;
_pageControl.currentPage =0;
_currentPageNo =0;
// _leftView.image = [_delegate imageForIndex:number-1];
// _middleView.image = [_delegate imageForIndex:_currentPageNo];
int nextNo =_currentPageNo;
if (number >2) {
nextNo = _currentPageNo+1;
}
// _rightView.image = [_delegate imageForIndex:nextNo];
if ([self.delegaterespondsToSelector:@selector(imageURLForIndex:)]) {
[_leftViewsd_setImageWithURL:[_delegateimageURLForIndex:number-1]placeholderImage:[UIImagenew]completed:^(UIImage *image,NSError *error,SDImageCacheType cacheType,NSURL *imageURL) {
// NSLog(@"");
}];
[_middleViewsd_setImageWithURL:[_delegateimageURLForIndex:_currentPageNo]placeholderImage:[UIImagenew]completed:^(UIImage *image,NSError *error,SDImageCacheType cacheType,NSURL *imageURL) {
}];
[_rightViewsd_setImageWithURL:[_delegateimageURLForIndex:nextNo]placeholderImage:[UIImagenew]completed:^(UIImage *image,NSError *error,SDImageCacheType cacheType,NSURL *imageURL) {
}];
} elseif ([self.delegaterespondsToSelector:@selector(imageForIndex:)]){
_leftView.image = [_delegateimageForIndex:number-1];
_middleView.image = [_delegateimageForIndex:_currentPageNo];
_rightView.image = [_delegateimageForIndex:nextNo];
}
}
if ([_delegaterespondsToSelector:@selector(didSelectAtIndex:)]) {
_middleView.userInteractionEnabled =YES;
UITapGestureRecognizer *tap = [[UITapGestureRecognizeralloc]initWithTarget:selfaction:@selector(selectAction:)];
[_middleViewaddGestureRecognizer:tap];
}
}
-(void)selectAction:(UITapGestureRecognizer *)gesture {
if ([self.delegaterespondsToSelector:@selector(didSelectAtIndex:)]) {
[self.delegatedidSelectAtIndex:_currentPageNo];
}
}
-(void)autoLoop{
_currentPageNo++;
//自动循环
[_scrollViewscrollRectToVisible:CGRectMake(_scrollView.bounds.size.width*2,0,_scrollView.bounds.size.width,_scrollView.bounds.size.height)animated:YES];
}
- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView{
// NSLog(@"scrollViewDidEndDecelerating");
int pageNo = scrollView.contentOffset.x/scrollView.bounds.size.width;
long imgCount = [_delegatenumberOfImagesInScrollView];
// NSLog(@"pageNo : %i",pageNo);
if (pageNo ==0) {
_currentPageNo--;
} elseif (pageNo ==2){
_currentPageNo++;
}
if (_currentPageNo <0) {
_currentPageNo = (int)(imgCount -1);
} elseif (_currentPageNo > imgCount -1) {
_currentPageNo =0;
}
int previousPage =_currentPageNo -1;
if (previousPage <0) {
previousPage = (int)(imgCount -1);
}
int nextPage =_currentPageNo +1;
if (nextPage > imgCount-1) {
nextPage = 0;
}
_pageControl.currentPage =_currentPageNo;
if ([self.delegaterespondsToSelector:@selector(imageURLForIndex:)]) {
[_leftViewsd_setImageWithURL:[_delegateimageURLForIndex:previousPage]placeholderImage:[UIImagenew]completed:^(UIImage *image,NSError *error,SDImageCacheType cacheType,NSURL *imageURL) {
}];
[_middleViewsd_setImageWithURL:[_delegateimageURLForIndex:_currentPageNo]placeholderImage:[UIImagenew]completed:^(UIImage *image,NSError *error,SDImageCacheType cacheType,NSURL *imageURL) {
}];
[_rightViewsd_setImageWithURL:[_delegateimageURLForIndex:nextPage]placeholderImage:[UIImagenew]completed:^(UIImage *image,NSError *error,SDImageCacheType cacheType,NSURL *imageURL) {
}];
} elseif ([self.delegaterespondsToSelector:@selector(imageForIndex:)]){
_leftView.image = [_delegateimageForIndex:previousPage];
_middleView.image = [_delegateimageForIndex:_currentPageNo];
_rightView.image = [_delegateimageForIndex:nextPage];
}
_scrollView.contentOffset =CGPointMake(scrollView.bounds.size.width,0);
}
@end
关于自动循环，我们可以自定义，其实就是加一个NSTimer定时器，每过一定的时间让scrollView滑向下一个View，即：
[_scrollViewscrollRectToVisible:CGRectMake(_scrollView.bounds.size.width*2,0,_scrollView.bounds.size.width,_scrollView.bounds.size.height)animated:YES];
scrollView会自动的滑向第三个View。然后图片就可以自动定时滑动了。
使用上述自定义的轮转图片时，一定要遵守UIScrollViewDelegate协议并实现代理方法，否则不可用。