iOS开发中,常碰到网络图片需要做尺寸适配(使显示出来的图片不变形) ,最好的解决方案是:后台把图片的分辨率拼接在图片的URL地址中,我们截取获得分辨率,从而根据宽高比,来适配imageView尺寸. ,但当后台所给图片URL地址中没有分辨率,他又不肯加时,只好我们自己来解决了. ,正好前段时间有这个需求,故特意写了一个工具XHWebImageAutoSize,来处理这个问题.
效果:
XHWebImageAutoSize特性:
- 1.异步缓存网络图片尺寸,优先从缓存中获取图片尺寸.
- 2.UITableView,UICollectionView动态刷新UI.
工作原理:
- 1.XHWebImageAutoSize的工作原理很简单,就是在首次加载网络图片后,缓存该图片的尺寸,下次直接调用缓存的尺寸.
API:
/**
* Get image height
*
* @param url imageURL
* @param layoutWidth layoutWidth
* @param estimateHeight estimateHeight(default 100)
*
* @return imageHeight
*/
+(CGFloat)imageHeightForURL:(NSURL *)url layoutWidth:(CGFloat)layoutWidth estimateHeight:(CGFloat )estimateHeight;
/**
* Get image size from cache,query the disk cache synchronously after checking the memory cache
*
* @param url imageURL
*
* @return imageSize
*/
+(CGSize )imageSizeFromCacheForURL:(NSURL *)url;
/**
* Store an imageSize into memory and disk cache
*
* @param image image
* @param url imageURL
* @param completedBlock An block that should be executed after the imageSize has been saved (optional)
*/
+(void)storeImageSize:(UIImage *)image forURL:(NSURL *)url completed:(XHWebImageAutoSizeCacheCompletionBlock)completedBlock;
/**
* Get reload state from cache,query the disk cache synchronously after checking the memory cache
*
* @param url imageURL
*
* @return reloadState
*/
+(BOOL)reloadStateFromCacheForURL:(NSURL *)url;
/**
* Store an reloadState into memory and disk cache
*
* @param state reloadState
* @param url imageURL
* @param completedBlock An block that should be executed after the reloadState has been saved (optional)
*/
+(void)storeReloadState:(BOOL)state forURL:(NSURL *)url completed:(XHWebImageAutoSizeCacheCompletionBlock)completedBlock;
- 2.tableView reload相关
/**
* Reload row
*
* @param indexPath indexPath
* @param url imageURL
*/
-(void)xh_reloadRowAtIndexPath:(NSIndexPath *)indexPath forURL:(NSURL *)url;
/**
* Reload row withRowAnimation
*
* @param indexPath indexPath
* @param animation UITableViewRowAnimation
* @param url imageURL
*/
-(void)xh_reloadRowAtIndexPath:(NSIndexPath *)indexPath withRowAnimation:(UITableViewRowAnimation)animation forURL:(NSURL *)url;
- 3.collectionView reload相关
/**
* Reload item
*
* @param indexPath indexPath
* @param url imageURL
*/
-(void)xh_reloadItemAtIndexPath:(NSIndexPath *)indexPath forURL:(NSURL *)url;
使用方法:
- 此处以在UITableView中使用,UITableViewCell上仅有一个UIImageView为例,其他示例详见-»>DEMO
-(CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath
{
NSString *url = self.dataArray[indexPath.row];
/**
* 参数1:图片URL
* 参数2:imageView 宽度
* 参数3:预估高度(此高度仅在图片尚未加载出来前起作用,不影响真实高度)
*/
return [XHWebImageAutoSize imageHeightForURL:[NSURL URLWithString:url] layoutWidth:[UIScreen mainScreen].bounds.size.width-16 estimateHeight:200];
}
-(UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
DemoVC1Cell *cell = [tableView dequeueReusableCellWithIdentifier:cellId];
if(!cell)
{
cell = [[DemoVC1Cell alloc]initWithStyle:UITableViewCellStyleDefault reuseIdentifier:cellId];
}
NSString *url = self.dataArray[indexPath.row];
//加载网络图片使用SDWebImage
[cell.imgView sd_setImageWithURL:[NSURL URLWithString:url] completed:^(UIImage *image, NSError *error, SDImageCacheType cacheType, NSURL *imageURL) {
/**
* 缓存image size
*/
[XHWebImageAutoSize storeImageSize:image forURL:imageURL completed:^(BOOL result) {
/**
* 尺寸缓存成功,reload cell
*/
if(result) [tableView xh_reloadRowAtIndexPath:indexPath forURL:imageURL];
}];
}];
}];
return cell;
}