iOS: 无限循环轮播图简单封装
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轮播图思路：
1.首先要有一个ScrollView和两张图片，把图片放到ScrollView上。
2.要想滚动ScrollView的宽度需设置屏宽的2倍。
3.循环滚动，当滚动到最后一张图片时，采用偏移的方法，将偏移量归零，回到第一张图片。
4.将第二张的图片上的所有值赋给第一张图片。
5.设置让它自己滚动，需添加定时器。
需要的第三方数据库:SDWebImage
m.文件内：
#imporst "ScrollView.h"
@interface ScrollView ()<UIScrollViewDelegate>
//滚动视图
@property (nonatomic,strong) UIScrollView *scrollView;
//图片
@property (nonatomic,strong) UIImageView *leftImageView;
//图片
@property (nonatomic,strong) UIImageView *rightImageView;
//指示小圆点
@property (nonatomic,strong) UIPageControl *pageControl;
//下标
@property (nonatomic,assign) NSInteger index;
//定时器
@property (nonatomic,strong) NSTimer *timer;
//接收外面传进来的值
@property (nonatomic,strong) NSArray *dataArray;
@end
@implementation ScrollView
//滚动视图的懒加载
- (UIScrollView *)scrollView{
if (!_scrollView) {
//初始化滚动视图
_scrollView = [[UIScrollView alloc]initWithFrame:CGRectMake(0, 0, self.frame.size.width, self.frame.size.height)];
//设置代理
_scrollView.delegate = self;
//取消反弹效果
_scrollView.bounces = NO;
_scrollView.bouncesZoom = NO;
//设置整页翻滚
_scrollView.pagingEnabled = YES;
//滚动范围
_scrollView.contentSize = CGSizeMake(self.frame.size.width*2, 0);
//滚动条的关闭
_scrollView.showsHorizontalScrollIndicator = NO;
}
return _scrollView;
}
//左边图片懒加载
- (UIImageView *)leftImageView{
if (!_leftImageView) {
//初始化图片框架
_leftImageView = [[UIImageView alloc]initWithFrame:CGRectMake(0, 0, self.frame.size.width, self.frame.size.height)];
//添加图片（写这步需要引入第三方数据库）
[_leftImageView sd_setImageWithURL:[NSURL URLWithString: self.dataArray[0]]];
}
return _leftImageView;
}
//右边图片懒加载
- (UIImageView *)rightImageView{
if (!_rightImageView) {
//初始化图片框架
_rightImageView = [[UIImageView alloc]initWithFrame:CGRectMake(self.leftImageView.frame.size.width, 0, self.frame.size.width, self.frame.size.height)];
//添加图片（写这步需要引入第三方数据库）
[_rightImageView sd_setImageWithURL:[NSURL URLWithString:self.dataArray[self.index]]];
}
return _rightImageView;
}
//小圆点指示标懒加载
- (UIPageControl *)pageControl{
if (!_pageControl) {
//初始化小圆点
_pageControl = [[UIPageControl alloc]initWithFrame:CGRectMake(50, self.scrollView.frame.size.height-50, self.frame.size.width-100, 50)];
// 设置页数
_pageControl.numberOfPages = self.dataArray.count;
// 设置圆点指示器的小圆点颜色
_pageControl.pageIndicatorTintColor = [UIColor redColor];
// 设置当前小圆点的颜色
_pageControl.currentPageIndicatorTintColor = [UIColor greenColor];
}
return _pageControl;
}
//定时器懒加载
- (NSTimer *)timer{
if (!_timer) {
//定时时间及事件
_timer = [NSTimer scheduledTimerWithTimeInterval:2 target:self selector:@selector(timerAction) userInfo:nil repeats:YES];
}
return _timer;
}
//重写父类
- (instancetype)initWithFrame:(CGRect)frame dataArray:(NSArray *)dataArray{
if ([super initWithFrame:frame]) {
//第一张图片
self.index = 1;
//将外面的值引入
self.dataArray = dataArray;
[self creatScrollViewWithFrame:frame];
}
return self;
}
//创建滚动视图
- (void)creatScrollViewWithFrame:(CGRect)frame {
[self.scrollView addSubview:self.leftImageView];
[self.scrollView addSubview:self.rightImageView];
[self addSubview:self.scrollView];
[self addSubview:self.pageControl];
dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(2 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
[self.timer fire];
});
}
//代理方法
- (void)scrollViewDidScroll:(UIScrollView *)scrollView{
//如果滚动视图的偏移量为屏幕宽
if (scrollView.contentOffset.x == self.frame.size.width) {
//返回0
self.scrollView.contentOffset = CGPointZero;
//当前小圆点为下标
self.pageControl.currentPage = self.index;
//下标加＋
self.index++;
//数组的下标设置为index
if (self.index == self.dataArray.count) {
//从0开始
self.index = 0;
}
//图片之间传值
self.leftImageView.image = self.rightImageView.image;
[self.rightImageView sd_setImageWithURL:[NSURL URLWithString:self.dataArray[self.index]]];
}
}
//定时器事件
- (void)timerAction{
[self.scrollView setContentOffset:CGPointMake(self.frame.size.width, 0) animated:YES];
}
h.文件内：
#import <UIKit/UIKit.h>
@interface ScrollView : UIView
- (instancetype)initWithFrame:(CGRect)frame dataArray:(NSArray *)dataArray;
@end
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