前言
相信大家在項(xiàng)目中很多都遇到過這樣的需求缨睡，要求實(shí)現(xiàn)圖片的循環(huán)滾動(dòng)播放，我這里使用scrollview實(shí)現(xiàn)蚊逢，先來說大體思路：首先創(chuàng)建一個(gè)scrollview聂宾，將其等分為三等份，然后根據(jù)定時(shí)器觸發(fā)滾動(dòng)虚倒，當(dāng)滾動(dòng)到最后或者第一個(gè)區(qū)域時(shí)美侦，將當(dāng)前的contentoffset手動(dòng)設(shè)置到中間2號(hào)區(qū)域，相當(dāng)于每次的滾動(dòng)完之后當(dāng)前位置都在2號(hào)區(qū)域魂奥；接下來菠剩，就看代碼了
代碼實(shí)現(xiàn)
首先，設(shè)置好scrollview耻煤，并且拿到需要顯示的images具壮，我這快使用代理模式，拿到需要顯示的圖片總數(shù)和當(dāng)前三個(gè)區(qū)域需要顯示的圖片哈蝇，然后設(shè)置當(dāng)前contenoffset為二號(hào)區(qū)域棺妓，最后開啟定時(shí)器，進(jìn)行滾動(dòng)播放炮赦，這里的imageviews實(shí)現(xiàn)了復(fù)用怜跑，只需要?jiǎng)?chuàng)建三個(gè)imageview：
- (void)reloadData
{
_currentPage = 0;
_totalPageCount = 0;
if (self.delegate && [self.delegate respondsToSelector:@selector(numberOfTotalScrollCount)]) {
_totalPageCount = [self.delegate numberOfTotalScrollCount];
if (_totalPageCount <= 1) {
[_timer pause];
}
}else{
}
[self resetScrollView];
}
- (void)resetScrollView
{
[_scrollView.subviews makeObjectsPerformSelector:@selector(removeFromSuperview)];
NSInteger preIndex = [self getPreIndex:_currentPage];
NSInteger curIndex = _currentPage;
NSInteger nextIndex = [self getNextIndex:_currentPage];
if (self.delegate && [self.delegate respondsToSelector:@selector(imageForScrollInIndex:)]) {
UIImage *preImage = [self.delegate imageForScrollInIndex:preIndex];
UIImage *curImage = [self.delegate imageForScrollInIndex:curIndex];
UIImage *nextImage = [self.delegate imageForScrollInIndex:nextIndex];
NSArray *images = @[preImage, curImage, nextImage];
for (int i = 0; i < images.count; i++) {
UIImageView *imageView = _imageViews[i];
switch (_direction) {
case ScrollPictureDirectionRight:
case ScrollPictureDirectionLeft:
[imageView setFrame:CGRectMake(i * OwnWidth_LCY, 0, OwnWidth_LCY, OwnHeight_LCY)];
break;
case ScrollPictureDirectionTop:
case ScrollPictureDirectionBottom:
[imageView setFrame:CGRectMake(0, i * OwnHeight_LCY, OwnWidth_LCY, OwnHeight_LCY)];
break;
default:
break;
}
[imageView setImage:images[i]];
[_scrollView addSubview:imageView];
}
[_scrollView setContentOffset:(_direction == ScrollPictureDirectionRight || _direction == ScrollPictureDirectionLeft) ? CGPointMake(OwnWidth_LCY, 0) : CGPointMake(0, OwnHeight_LCY)];
}
}
在定時(shí)器中，我們需要實(shí)現(xiàn)scrollview的滾動(dòng)眼五，即妆艘，根據(jù)方向設(shè)置其contentoffset代碼如下：
- (void)start:(NSTimer *)timer
{
CGFloat contentOffsetX = _scrollView.contentOffset.x;
CGFloat contentOffSetY = _scrollView.contentOffset.y;
switch (_direction) {
case ScrollPictureDirectionLeft:
contentOffsetX += OwnWidth_LCY;
break;
case ScrollPictureDirectionRight:
contentOffsetX -= OwnWidth_LCY;
break;
case ScrollPictureDirectionTop:
contentOffSetY += OwnHeight_LCY;
break;
case ScrollPictureDirectionBottom:
contentOffSetY -= OwnHeight_LCY;
break;
default:
break;
}
CGPoint contentOffset = CGPointMake(contentOffsetX, contentOffSetY);
[_scrollView setContentOffset:contentOffset animated:YES];
}
邊界處理彤灶，當(dāng)當(dāng)前顯示的圖片是數(shù)組中最后一個(gè)或者第一個(gè)圖片時(shí)，需要進(jìn)行處理批旺，刷新當(dāng)前需要顯示的image幌陕；
那么我們?cè)谑裁磿r(shí)候得知試圖當(dāng)前的滾動(dòng)位置呢，無疑我們應(yīng)該在其代理函數(shù)里面獲取汽煮，并且進(jìn)行處理搏熄，這里我實(shí)現(xiàn)了上下左右四個(gè)方向的滾動(dòng)，可以根據(jù)參數(shù)選取不同的方向暇赤，原理是一樣的：
- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
CGPoint contentSize = _scrollView.contentOffset;
switch (_direction) {
case ScrollPictureDirectionRight:
{
if (contentSize.x <= 0){
_currentPage = [self getPreIndex:_currentPage];
[self resetScrollView];
if (self.delegate && [self.delegate respondsToSelector:@selector(scrollAtTheIndex:)]) {
[self.delegate scrollAtTheIndex:_currentPage];
}
}
}
break;
case ScrollPictureDirectionBottom:
{
if (contentSize.y <= 0){
_currentPage = [self getPreIndex:_currentPage];
[self resetScrollView];
if (self.delegate && [self.delegate respondsToSelector:@selector(scrollAtTheIndex:)]) {
[self.delegate scrollAtTheIndex:_currentPage];
}
}
}
break;
case ScrollPictureDirectionLeft:
{
if (contentSize.x >= OwnWidth_LCY * 2) {
_currentPage = [self getNextIndex:_currentPage];
[self resetScrollView];
if (self.delegate && [self.delegate respondsToSelector:@selector(scrollAtTheIndex:)]) {
[self.delegate scrollAtTheIndex:_currentPage];
}
}
}
break;
case ScrollPictureDirectionTop:
{
if (contentSize.y >= OwnHeight_LCY * 2) {
_currentPage = [self getNextIndex:_currentPage];
[self resetScrollView];
if (self.delegate && [self.delegate respondsToSelector:@selector(scrollAtTheIndex:)]) {
[self.delegate scrollAtTheIndex:_currentPage];
}
}
}
break;
default:
break;
}
}
- (NSInteger)getPreIndex:(NSInteger)currentIndex
{
if (currentIndex == 0) {
return _totalPageCount - 1;
}
return currentIndex - 1;
}
- (NSInteger)getNextIndex:(NSInteger)currentIndex
{
if (currentIndex == _totalPageCount - 1) {
return 0;
}
return currentIndex + 1;
}
至此心例，所有的的關(guān)鍵代碼就結(jié)束了，這里的關(guān)鍵點(diǎn)是要理解當(dāng)scrollview滾動(dòng)到1號(hào)或者3號(hào)區(qū)域時(shí)鞋囊，需要重新設(shè)置當(dāng)前的contentoffset為2號(hào)區(qū)域止后，以此來實(shí)現(xiàn)無限滾動(dòng)；
ps：這里是代碼鏈接和使用～～
