之前有写过图片的定时无限轮播，不过无法做到平滑的效果（当图片显示到最后一张后会立刻跳转到第一页。而不是平滑的显示第一页）。
下有实现源码，不过在以（／／＊＊＊＊＊＊＊＊）为分割线的内部也既是对方法（- (void)scrollViewDidScroll:(UIScrollView *)scrollView）的算法实现不是很理解，不明白为什么，望大神指教。
轮播器是这样的：
// 1.添加5张图片到scrollView中
for (NSInteger i = 0; i < IMAGECOUNT; i++) {
UIImageView *imageView = [[UIImageView alloc] init];
// 设置frame
CGFloat imageX = i * imageW + imageW;
// CGFloat imageX = i * imageW;
// NSLog(@"imageX= %f i= %ld",imageX,i);
imageView.frame = CGRectMake(imageX , imageY, imageW, imageH);
// 设置图片
NSString *name = [NSString stringWithFormat:@"ad_0%ld", i];
imageView.image = [UIImage imageNamed:name];
[self.scrollView addSubview:imageView];
}
// 1.1 将最后一张图片放在第0个位置
UIImageView *lastImage = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"ad_04"]];
lastImage.frame = CGRectMake(0, 0, imageW, imageH);
[self.scrollView addSubview:lastImage];
// 1.2 将第一张图片放在最后1页
UIImageView *firstImage = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"ad_00"]];
firstImage.frame = CGRectMake((IMAGECOUNT + 1) * imageW, 0, imageW, imageH);
[self.scrollView addSubview:firstImage];
// 2.设置内容尺寸
CGFloat contentW = (IMAGECOUNT + 2) * imageW;
self.scrollView.contentSize = CGSizeMake(contentW, 0);
// 3.隐藏水平滚动条
// self.scrollView.showsHorizontalScrollIndicator = NO;
// 4.分页
self.scrollView.pagingEnabled = YES;
// 5.设置pageControl的总页数
self.pageControl.numberOfPages = IMAGECOUNT;
[self.scrollView setContentOffset:CGPointMake(imageW, 0)];
NSLog(@"offset= %@",NSStringFromCGPoint(self.scrollView.contentOffset));
self.pageControl.currentPage = 0;
// 6.添加定时器(每隔2秒调用一次self 的nextImage方法)
[self addTimer];
}
/**
* 添加定时器
*/
- (void)addTimer
{
self.timer = [NSTimer scheduledTimerWithTimeInterval:2.0 target:self selector:@selector(nextImage) userInfo:nil repeats:YES];
[[NSRunLoop currentRunLoop] addTimer:self.timer forMode:NSRunLoopCommonModes];
}
/**
* 移除定时器
*/
- (void)removeTimer
{
[self.timer invalidate];
self.timer = nil;
}
- (void)nextImage{
// 1.增加pageControl的页码
NSInteger page = self.pageControl.currentPage + 2; // 1
// NSLog(@"page= %ld",page);
// 2.计算scrollView滚动的位置
CGFloat offsetX = page * self.scrollView.frame.size.width; // 600
NSLog(@"currentPage= %ld,offsetX= %f,page= %ld",(long)self.pageControl.currentPage,offsetX,page);
CGPoint offset = CGPointMake(offsetX, 0);
[self.scrollView setContentOffset:offset animated:YES];
}
#pragma mark - 代理方法
/**
* 当scrollView正在滚动就会调用
*/
／／＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊
／／＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊
- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
// 根据scrollView的滚动位置决定pageControl显示第几页
CGFloat scrollW = scrollView.frame.size.width;
NSInteger page = (scrollView.contentOffset.x + scrollW * 0.5) / scrollW;
// if (page > 5) {
// self.pageControl.currentPage = 0;
// }else if (page == 0) {
// self.pageControl.currentPage = 5;
// } else {
// self.pageControl.currentPage = --page;
// }
page = (--page == 5) ? 0 : page;
self.pageControl.currentPage = (page == -1) ? 5 : page;
}
／／＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊
／／＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊
/**
* 开始拖拽的时候调用
*/
- (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView
{
// 停止定时器(一旦定时器停止了,就不能再使用)
[self removeTimer];
}
/**
* 停止拖拽的时候调用
*/
- (void)scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate
{
// 开启定时器
[self addTimer];
}
/** 当动画滚动时,动画结束,也就是滚动一页停止之后,会调用此方法 */
- (void)scrollViewDidEndScrollingAnimation:(UIScrollView *)scrollView{
[self scrollViewDidStop:scrollView];
}
/** 手动滚动时,当降速完也,也就是滚动一页停止之后,会调用此方法 */
- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView{
[self scrollViewDidStop:scrollView];
}
/**
* 当停止滚动的时候调用
*/
-(void)scrollViewDidStop:(UIScrollView *)scrollView{
CGFloat scrollW = scrollView.frame.size.width;
NSInteger page = (self.scrollView.contentOffset.x + 0.5 * scrollW) / scrollW;
if (page == 0){
[self.scrollView setContentOffset:CGPointMake(scrollW * IMAGECOUNT, 0)];
} else if (page == (IMAGECOUNT + 1)) {
[self.scrollView setContentOffset:CGPointMake(scrollW , 0)];
}
}
|
|
收藏
淘帖
踩
