Cacher is the code snippet organizer for pro developers

#import "LNCustomCollectionView.h"

// 单元格
@interface PhotoGalleryCell : UICollectionViewCell

// 照片
@property (strong, nonatomic) UIImageView *imageViewPhoto;

@end

// 视图
@interface PhotoGalleryCollectionView : LNCustomCollectionView

@end


#import "PhotoGalleryCollectionView.h"
#import "KSPhotoBrowser.h"

// 单元格
@implementation PhotoGalleryCell

- (instancetype)initWithFrame:(CGRect)frame {
    self = [super initWithFrame:frame];
    if (self) {
        // 照片
        UIImageView *imageViewPhoto = [UIImageView new];
        imageViewPhoto.layer.masksToBounds = YES;
        imageViewPhoto.contentMode = UIViewContentModeScaleAspectFill;
        [self.contentView addSubview:imageViewPhoto];
        [imageViewPhoto mas_makeConstraints:^(MASConstraintMaker *make) {
            make.top.left.bottom.right.offset(0);
        }];
        self.imageViewPhoto = imageViewPhoto;
    }
    return self;
}

@end

// 视图
@implementation PhotoGalleryCollectionView

- (void)commonInit {
    [super commonInit];
    
    UICollectionViewFlowLayout *layout = (UICollectionViewFlowLayout *)self.collectionViewLayout;
    layout.minimumInteritemSpacing = 5;
    layout.minimumLineSpacing = 5;
    
    [self registerClass:[PhotoGalleryCell class] forCellWithReuseIdentifier:@"PhotoGalleryCell"];
}

- (__kindof UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath {
    PhotoGalleryCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:@"PhotoGalleryCell" forIndexPath:indexPath];
    NSString *url = self.itemArray[indexPath.row];
    [cell.imageViewPhoto sd_setImageWithURL:FullImageUrl(url) placeholderImage:PLACEHOLDER_IMAGE];
    return cell;
}

- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath *)indexPath {
    const NSInteger kItemNumOfRow = 3;
    UICollectionViewFlowLayout *layout = (UICollectionViewFlowLayout *)self.collectionViewLayout;
    NSInteger row = indexPath.row;
    CGFloat totalWidth = self.frame.size.width - layout.sectionInset.left - layout.sectionInset.right - layout.minimumInteritemSpacing * (kItemNumOfRow - 1);
    CGFloat width;
    
    if (row % kItemNumOfRow) {
        width = roundf(totalWidth / kItemNumOfRow);
    } else {
        width = totalWidth - roundf(totalWidth / kItemNumOfRow) * (kItemNumOfRow - 1);
    }
    
    return CGSizeMake(width, width);
}

- (void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath {
    
    NSMutableArray *items = @[].mutableCopy;
    for (int i = 0; i < self.itemArray.count; i++) {
        KSPhotoItem *item = [KSPhotoItem itemWithSourceView:nil imageUrl:FullImageUrl(self.itemArray[i])];
        [items addObject:item];
    }
    KSPhotoBrowser *browser = [KSPhotoBrowser browserWithPhotoItems:items selectedIndex:indexPath.row];
    [browser showFromViewController:self.viewController];
}

- (UIViewController *)viewController {
    id nextResponder = [self nextResponder];
    while (nextResponder != nil) {
        if ([nextResponder isKindOfClass:[UIViewController class]]) {
            UIViewController *vc = (UIViewController *)nextResponder;
            return vc;
        }
        nextResponder = [nextResponder nextResponder];
    }
    return nil;
}

@end