scrollView 循环滚动

最新推荐文章于 2023-12-23 03:15:52 发布

moxi_wang

最新推荐文章于 2023-12-23 03:15:52 发布

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分类专栏： iOS UI 高级文章标签： scorllerview 循环滚动

本文链接：https://blog.youkuaiyun.com/moxi_wang/article/details/51008346

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本文介绍了一种在iOS应用中实现无限循环滚动图片的方法。通过在滚动视图两端添加首尾图片，确保了图片可以无缝循环展示。文章详细展示了如何使用UIButton作为图片载体，并通过scrollView代理方法处理滚动结束时的位置重置。

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思路：比需要创建的滚动图片多添加两个，在第一个图片前面把最后个添加进去，最后面个图片后面添加第一个图片。

1、在第一个显示的图片前面添加最后一张图片

UIButton *button0 = [UIButton buttonWithType:UIButtonTypeCustom];

button0.frame = CGRectMake(0, 0, kScreenwidth, CGRectGetHeight(__scrollerView.frame) - 64);

if (modelArray.count > 0) {

AdvertisementModel *model = [modelArray objectAtIndex:modelArray.count - 1];

//不为空

if (![model.imagehttp isEqual:[NSNull null]]) {

ImgData = [NSData dataWithContentsOfURL:[NSURL URLWithString:model.imagehttp]];

UIImage *img = [UIImage imageWithData:ImgData];

[button0 setBackgroundImage:img forState:UIControlStateNormal];

}else

{

[button0 setBackgroundImage:[UIImage imageNamed:[NSString stringWithFormat:@"pic%d.png",modelArray.count]] forState:UIControlStateNormal];

}

button0.tag = 99;

[button0 addTarget:self action:@selector(buttonAction:) forControlEvents:UIControlEventTouchUpInside];

[__scrollerView addSubview:button0];

}

2、添加需要添加的图片

for (int i = 1; i <= modelArray.count; i++) {

UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];

button.frame = CGRectMake(i*kScreenwidth, 0, kScreenwidth, CGRectGetHeight(__scrollerView.frame) - 64);

AdvertisementModel *model = [modelArray objectAtIndex:i - 1];

//不为空

if (![model.imagehttp isEqual:[NSNull null]]) {

ImgData = [NSData dataWithContentsOfURL:[NSURL URLWithString:model.imagehttp]];

UIImage *img = [UIImage imageWithData:ImgData];

[button setBackgroundImage:img forState:UIControlStateNormal];

}else

{

[button setBackgroundImage:[UIImage imageNamed:[NSString stringWithFormat:@"pic%d.png",i]] forState:UIControlStateNormal];

}

button.tag = 100 + i;

[button addTarget:self action:@selector(buttonAction:) forControlEvents:UIControlEventTouchUpInside];

[__scrollerView addSubview:button];

}

3、在最后面张图片后面添加第一张图

UIButton *button1 = [UIButton buttonWithType:UIButtonTypeCustom];

button1.frame = CGRectMake(kScreenwidth * (modelArray.count + 1), 0, kScreenwidth, CGRectGetHeight(__scrollerView.frame) - 64);

if (modelArray.count > 0) {

AdvertisementModel *model = [modelArray objectAtIndex:0];

//不为空

if (![model.imagehttp isEqual:[NSNull null]]) {

ImgData = [NSData dataWithContentsOfURL:[NSURL URLWithString:model.imagehttp]];

UIImage *img = [UIImage imageWithData:ImgData];

[button1 setBackgroundImage:img forState:UIControlStateNormal];

}else

{

[button1 setBackgroundImage:[UIImage imageNamed:@"pic1.png"] forState:UIControlStateNormal];

}

button1.tag = 98;

[button1 addTarget:self action:@selector(buttonAction:) forControlEvents:UIControlEventTouchUpInside];

[__scrollerView addSubview:button1];

}

4、设置偏移量指向第一张图

__scrollerView.contentOffset = CGPointMake(kScreenwidth, 0);

／／代理方法

-(void)scrollViewDidScroll:(UIScrollView *)scrollView

{

NSInteger page = (NSInteger)scrollView.contentOffset.x /kScreenwidth - 1;

_pageControl.currentPage = page;

}

-(void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView

{

NSInteger page = (NSInteger)scrollView.contentOffset.x /kScreenwidth;

if (page == 0) {

[__scrollerView scrollRectToVisible:CGRectMake(kScreenwidth*modelArray.count, 0, kScreenwidth, 256) animated:NO];

}

else if (page == modelArray.count + 1)

{

[__scrollerView scrollRectToVisible:CGRectMake(kScreenwidth, 0, kScreenwidth, 256) animated:NO];

}