新浪微博客户端(30)-制作微博中的九宫格相册图片

DJStatusPhotosView.h

#import <UIKit/UIKit.h>

@interface DJStatusPhotosView : UIView

@property (nonatomic,strong) NSArray *photos;

/** 根据相册图片个数计算相册尺寸 */
+ (CGSize)sizeWithCount:(NSUInteger)count;

@end

DJStatusPhotosView.m

#import "DJStatusPhotosView.h"
#import "UIImageView+WebCache.h"
#import "DJPhoto.h"

// 相册的最大列数
#define DJStatusPhotosViewMaxColumns 3
// 相册中的图片间距
#define DJStatusPhotosViewMargin 4
// 相册图片的宽高
#define DJStatusPhotoWH ((DJContentWidth - (DJStatusPhotosViewMaxColumns - 1) * DJStatusPhotosViewMargin) / DJStatusPhotosViewMaxColumns)

@implementation DJStatusPhotosView

- (instancetype)initWithFrame:(CGRect)frame
{
    self = [super initWithFrame:frame];
    if (self) {
//        self.backgroundColor = [UIColor redColor];
    }
    return self;
}

+ (CGSize)sizeWithCount:(NSUInteger)count {

    // 相册列数
    NSUInteger cols = (count >= DJStatusPhotosViewMaxColumns ) ? DJStatusPhotosViewMaxColumns : count;
    // 相册宽度
    CGFloat photosW = cols * DJStatusPhotoWH + (cols-1) * DJStatusPhotosViewMargin;

    /*
     *  补充公式：
     *  一共268条数据,每页18条,共有多少页,计算公式如下
     *  int pages = (totalCount + maxNumsInPage - 1) / maxNumsInPage
     */

    // 相册行数
    NSUInteger rows = (count + DJStatusPhotosViewMaxColumns - 1) / DJStatusPhotosViewMaxColumns;
    CGFloat photosH = rows * DJStatusPhotoWH + (rows-1) * DJStatusPhotosViewMargin;

    return CGSizeMake(photosW,photosH);
}

- (void)setPhotos:(NSArray *)photos {

    _photos = photos;

    // 添加和创建所需的UIImageView,并且设置图片的显示内容
    NSUInteger photosCount = photos.count;

    // 令相册里的photoView的个数始终满足待显示的需要，若数组中的图片个数大于相册中现有的个数，则创建新的photoView
    while (self.subviews.count < photosCount) {
        UIImageView *photoView = [[UIImageView alloc] init];
        [self addSubview:photoView];
    }

    // 设置相册中的imageView的显示内容
    for (int i = 0; i < self.subviews.count; i++) {
        UIImageView *photoView = self.subviews[i];
        if (i >= photosCount) { // 当前photoView多余，将其hidden属性置为YES,因为tableView的cell会重复利用
            photoView.hidden = YES;
        } else {
            photoView.hidden = NO;
            DJPhoto *photo = photos[i];
            [photoView sd_setImageWithURL:[NSURL URLWithString:photo.thumbnail_pic] placeholderImage:[UIImage imageNamed:@"timeline_image_placeholder"]];
        }

    }

}

// 在此方法中设置相册中单个图片的frame
- (void)layoutSubviews {

    [super layoutSubviews];

    for (int i = 0; i < self.photos.count; i++) {
        UIImageView *photoView = self.subviews[i];
        int col = i % DJStatusPhotosViewMaxColumns;
        photoView.x = col * (DJStatusPhotoWH + DJStatusPhotosViewMargin);

        int row = i / DJStatusPhotosViewMaxColumns;
        photoView.y = row * (DJStatusPhotoWH + DJStatusPhotosViewMargin);

        photoView.width = DJStatusPhotoWH;
        photoView.height = DJStatusPhotoWH;
    }

}

@end

最终效果：