前言
本文主要給大家介紹了關于iOS實現系統相冊大圖瀏覽功能的相關資料，分享出來供大家參考學習，下面話不多說了，來一起看看詳細的介紹吧。
最終效果圖
大圖瀏覽
實現過程
實現原理
創建collectionView非常簡單，只要正常創建就好，值得注意的是：由于需要當前展示的圖片的縮略圖始終保持在屏幕中間位置，所以在創建縮略圖的collectionView的時候需要對collection View設置好便宜量。
- (UIEdgeInsets)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout insetForSectionAtIndex:(NSInteger)section{return UIEdgeInsetsMake(0, (kScreenWidth - _itemWidth)/2, 0, (kScreenWidth - _itemWidth)/2);}實現上下聯動通過兩個block來實現
-(void)collectionViewDidScrollWithScrollBlock:(DidScrollBlock)didScrollBlcok;-(void)collectionViewDidScrollWithScrollBlock:(IndexScrollBlock)didScrollBlcok;
實現當前顯示縮略圖放大通過設置collectionView的UICollectionViewFlowLayout實現
IndexFlow *flowLayout = [[IndexFlow alloc] init];self = [super initWithFrame:frame collectionViewLayout:flowLayout];
部分實現代碼
- (void)collectionViewDidScrollWithScrollBlock:(DidScrollBlock)didScrollBlcok{self.didScrollBlcok = didScrollBlcok;}- (BOOL)gestureRecognizerShouldBegin:(UIGestureRecognizer *)gestureRecognizer{self.shouldDid = YES;return YES;}- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView{self.shouldDid = NO;}- (void)scrollViewDidScroll:(UIScrollView *)scrollView{ if (self.shouldDid) { if (self.didScrollBlcok) { self.didScrollBlcok(self); } }}- (UIEdgeInsets)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout insetForSectionAtIndex:(NSInteger)section{return UIEdgeInsetsMake(0, (kScreenWidth - _itemWidth)/2, 0, (kScreenWidth - _itemWidth)/2);}- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath *)indexPath{return CGSizeMake(_itemWidth, self.height);}- (CGFloat)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout minimumLineSpacingForSectionAtIndex:(NSInteger)section{return _minLineSpacing;}縮略圖放大實現代碼
- (BOOL)shouldInvalidateLayoutForBoundsChange:(CGRect)oldBounds{return YES;}-(NSArray*)layoutAttributesForElementsInRect:(CGRect)rect{// 取出所有元素NSArray *array = [super layoutAttributesForElementsInRect:rect];// 可視區域CGRect visibleRect;visibleRect.origin = self.collectionView.contentOffset;visibleRect.size = self.collectionView.bounds.size; for (UICollectionViewLayoutAttributes *attribute in array) { CGFloat distance = CGRectGetMidX(visibleRect) - attribute.center.x; CGFloat normalizedDistance = distance / ACTIVE_DISTANCE; if (ABS(distance) < ACTIVE_DISTANCE) { CGFloat zoom = 1 + ZOOM_FACTOR*(1 - ABS(normalizedDistance)); attribute.transform3D = CATransform3DMakeScale(zoom, zoom, 1.0); attribute.zIndex = 1; }}return array;}/** * 設置collectionView停止滾動那一刻的位置 * * @param proposedContentOffset 原本collectionView停止滾動那一刻的位置 * @param velocity 速度 * * @return 最終的位置 */- (CGPoint)targetContentOffsetForProposedContentOffset:(CGPoint)proposedContentOffset withScrollingVelocity:(CGPoint)velocity{CGFloat offsetAdjustment = MAXFLOAT;CGFloat horizontalCenter = proposedContentOffset.x + (CGRectGetWidth(self.collectionView.bounds) / 2.0);// 停止時刻的可視區域CGRect targetRect = CGRectMake(proposedContentOffset.x, 0.0, self.collectionView.bounds.size.width, self.collectionView.bounds.size.height);NSArray* array = [super layoutAttributesForElementsInRect:targetRect];for (UICollectionViewLayoutAttributes* layoutAttributes in array) { CGFloat itemHorizontalCenter = layoutAttributes.center.x; if (ABS(itemHorizontalCenter - horizontalCenter) < ABS(offsetAdjustment)) { offsetAdjustment = itemHorizontalCenter - horizontalCenter; }}return CGPointMake(proposedContentOffset.x + offsetAdjustment, proposedContentOffset.y);}源碼下載：
總結
以上就是這篇文章的全部內容了，希望本文的內容對大家的學習或者工作能帶來一定的幫助，如果有疑問大家可以留言交流，謝謝大家對VEVB武林網的支持。
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