项目开发中经常遇到首页要用到Banner页轮播图片，基于性能和用户体验性考虑，使用ScrollView+UIImageView来实现，设计思想：用三个UIImageView来显示图片，中间的centerImageView显示当前索引下的图片，leftImageView显示前一张图片，rightImageView显示后一张图片。每当scrollView滑动停止时，重新设置三张ImageView的图片，并让scrollView显示中间额centerImageView。
公有方法
/*初始化*/
-(id)initWithFrame:(CGRect)frame withUrlArr:(NSArray *)urlArr withTapBlock:(void(^)(NSInteger selectIndex)) block;
-(id)initWithFrame:(CGRect)frame withImgArr:(NSArray *)imgArr withTapBlock:(void(^)(NSInteger selectIndex)) block;
/*动画*/
-(void)startAnimationWithInterval:(NSInteger)interval;
-(void)stopAnimation;
私有属性
{
BOOL _isUrl;
}
@property(nonatomic,copy)void (^tapBlock)(NSInteger selectIndex);
@property(nonatomic,strong)UIScrollView *scrollView;
@property(nonatomic,strong)UIPageControl *pageControl;
@property(nonatomic,strong)NSTimer *timer;
@property(nonatomic)NSInteger currentImageIndex;
@property(nonatomic,strong)UIImageView *leftImageView;
@property(nonatomic,strong)UIImageView *centerImageView;
@property(nonatomic,strong)UIImageView *rightImageView;
@property(nonatomic,copy)NSArray *imgArr;
@property(nonatomic,copy)NSArray *urlArr;
核心代码
-（void）reloadImage
{
NSInteger leftImageIndex,rightImageIndex;
CGPoint offset=[_scrollView contentOffset];
if (offset.x>CGRectGetWidth(self.frame)) { //向右滑动
_currentImageIndex=(_currentImageIndex+1)%self.pageControl.numberOfPages;
}else if(offset.x<CGRectGetWidth(self.frame)){ //向左滑动
_currentImageIndex=(_currentImageIndex+self.pageControl.numberOfPages-1)%self.pageControl.numberOfPages;
}
leftImageIndex=(_currentImageIndex+self.pageControl.numberOfPages-1)%self.pageControl.numberOfPages;
rightImageIndex=(_currentImageIndex+1)%self.pageControl.numberOfPages;
if(_isUrl)
{
[_centerImageView sd_setImageWithURL:[NSURL URLWithString:_urlArr[_currentImageIndex]]];
[_leftImageView sd_setImageWithURL:[NSURL URLWithString:_urlArr[leftImageIndex]]];
[_rightImageView sd_setImageWithURL:[NSURL URLWithString:_urlArr[rightImageIndex]]];
}else
{
_centerImageView.image=_imgArr[_currentImageIndex];
_leftImageView.image=_imgArr[leftImageIndex];
_rightImageView.image=_imgArr[rightImageIndex];
}
_pageControl.currentPage=_currentImageIndex;
}
