图片缩放

//自定义cell类，继承于UICollectionViewCell

@interface MyCell :UICollectionViewCell

@property (nonatomic,retain) UIScrollView *scrollView;

@property (nonatomic,retain) UIImageView *showImgView;

@end

@implementation MyCell

- (id)initWithFrame:(CGRect)frame {

self= [super initWithFrame:frame];

if(self) {

[self addSubview:self.scrollView];

}

return self;

}

- (UIImageView *)showImgView {

if(!_showImgView) {

_showImgView = [[UIImageView alloc] init];

_showImgView.frame = self.bounds;

}

return _showImgView;

}

- (UIScrollView *)scrollView {

if(!_scrollView) {

_scrollView= [[UIScrollView alloc] initWithFrame:self.bounds];

_scrollView.delegate=self;

//设置图片缩放比例

_scrollView.minimumZoomScale= 0.5f;

_scrollView.maximumZoomScale= 2.0f;

[_scrollView addSubview:self.showImgView];

}

return _scrollView;

}

#pragma mark --- UIScrollViewDelegate

- (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView {

return _showImgView;

}

- (void)scrollViewDidZoom:(UIScrollView *)scrollView {

CGFloat offsetX = scrollView.bounds.size.width> scrollView.contentSize.width? (scrollView.bounds.size.width- scrollView.contentSize.width) * 0.5 : 0.0;

CGFloat offsetY = scrollView.bounds.size.height> scrollView.contentSize.height? (scrollView.bounds.size.height- scrollView.contentSize.height) * 0.5 : 0.0;

_showImgView.center = CGPointMake(scrollView.contentSize.width/2 + offsetX, scrollView.contentSize.height/2 + offsetY);

}

---

#import"MyCell.h"

#define WIDTH [UIScreen mainScreen].bounds.size.width

#define HEIGHT [UIScreen mainScreen].bounds.size.height

@interfaceViewController()

@property (nonatomic, retain) UICollectionView *collectionView;

@property (nonatomic, retain) NSMutableArray *imageArray;

@end

@implementation ViewController

- (void)viewDidLoad {

[super viewDidLoad];

//创建图片

[self createImageArray];

//设置collectionView

[self.view addSubview:self.collectionView];

}

- (void)createImageArray {

_imageArray= [NSMutableArray array];

for(int i = 0; i<9; i++) {

UIImage *image = [UIImage imageNamed:[NSStringstringWithFormat:@"%d.jpg",i+1]];

[_imageArray addObject:image];

}

}

- (UICollectionView *)collectionView {

if(!_collectionView) {

//布局

UICollectionViewFlowLayout *layout = [[UICollectionViewFlowLayout alloc] init];

layout.minimumLineSpacing = 0;

layout.minimumInteritemSpacing = 0;

[layout setItemSize:CGSizeMake(WIDTH,HEIGHT)];

layout.sectionInset = UIEdgeInsetsMake(0, 0, 0, 0);

layout.scrollDirection = UICollectionViewScrollDirectionHorizontal;

_collectionView= [[UICollectionView alloc] initWithFrame:self.view.frame collectionViewLayout:layout];

_collectionView.delegate = self;

_collectionView.dataSource = self;

_collectionView.pagingEnabled = YES;

//_collectionView.minimumZoomScale = 0.5f;

//_collectionView.maximumZoomScale = 2.0f;

[_collectionView registerClass:[MyCell class] forCellWithReuseIdentifier:@"cell"];

}

return _collectionView;

}

//- (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView {

//    int index = _collectionView.contentOffset.x / WIDTH;

//    MyCell *cell = self.collectionView.subviews[index];

//    return cell.showImgView;

//}

- (NSInteger)collectionView:(UICollectionView*)collectionView numberOfItemsInSection:(NSInteger)section {

return _imageArray.count;

}

- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath {

MyCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:@"cell" forIndexPath:indexPath];

//在cell上显示图片

cell.showImgView.image= [_imageArray objectAtIndex:indexPath.row];

//对cell上的图片大小进行操作

[self resetImageWithImgView:cell.showImgView];

//每次加载视图时让滑动视图的缩放系数为1

cell.scrollView.zoomScale= 1.0f;

returncell;

}

- (void)resetImageWithImgView:(UIImageView *)imgView {

//获取图片的原始宽高

CGSize size = imgView.image.size;

//获取缩放比例

CGFloat xScale = WIDTH/ size.width;

CGFloat yScale = HEIGHT/ size.height;

//以小的为标准

if(xScale < yScale) {

CGRect rect = imgView.frame;

rect.size.width=WIDTH;

rect.size.height = size.height * xScale;

imgView.frame= rect;

}else{

CGRect rect = imgView.frame;

rect.size.height=HEIGHT;

rect.size.width = size.width* yScale;

imgView.frame = rect;

}

//居中

imgView.center = self.view.center;

}