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New option SDWebImageRefreshCached 

Even if the image is cached, fetch the URL again anyway. When set,
NSURLCache is enabled in the downloader via the new option
SDWebImageDownloaderEnableNSURLCache.

NSURLCache will handle the protocol caching while SDWebImage remains
useful for offline images.

This option helps deal with images changing behind the same request URL,
e.g. Facebook graph api profile pics where the request URL
https://graph.facebook.com/[userid]/picture returns a redirect to the
actual profile image.

If a cached image exists, the completion block is called once with the
cached image and again with the final image.
This commit is contained in:
Steven Chan 2013-03-12 01:08:57 +08:00
parent 95337c47e9
commit bbad1bcfcc
4 changed files with 21 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
SDWebImage/SDWebImageDownloader.h
View File

@ -13,7 +13,8 @@
typedef enum
{
SDWebImageDownloaderLowPriority = 1 << 0,
SDWebImageDownloaderProgressiveDownload = 1 << 1
SDWebImageDownloaderProgressiveDownload = 1 << 1,
SDWebImageDownloaderEnableNSURLCache = 1 << 2
} SDWebImageDownloaderOptions;
typedef enum

2
SDWebImage/SDWebImageDownloader.m
View File

@ -120,7 +120,7 @@ static NSString *const kCompletedCallbackKey = @"completed";
[self addProgressCallback:progressBlock andCompletedBlock:completedBlock forURL:url createCallback:^
{
// In order to prevent from potential duplicate caching (NSURLCache + SDImageCache) we disable the cache for image requests
NSMutableURLRequest *request = [NSMutableURLRequest.alloc initWithURL:url cachePolicy:NSURLRequestReloadIgnoringLocalCacheData timeoutInterval:15];
NSMutableURLRequest *request = [NSMutableURLRequest.alloc initWithURL:url cachePolicy:(options & SDWebImageDownloaderEnableNSURLCache ? NSURLRequestUseProtocolCachePolicy : NSURLRequestReloadIgnoringLocalCacheData) timeoutInterval:15];
request.HTTPShouldHandleCookies = NO;
request.HTTPShouldUsePipelining = YES;
request.allHTTPHeaderFields = wself.HTTPHeaders;

9
SDWebImage/SDWebImageManager.h
View File

@ -31,7 +31,14 @@ typedef enum
* This flag enables progressive download, the image is displayed progressively during download as a browser would do.
* By default, the image is only displayed once completely downloaded.
*/
SDWebImageProgressiveDownload = 1 << 3
SDWebImageProgressiveDownload = 1 << 3,
/**
* Even if the image is cached, fetch the URL again anyway. When set, NSURLCache is enabled in the downloader.
* NSURLCache will handle the protocol caching logic while SDWebImage remains useful for offline images.
* This option helps deal with images changing behind the same request URL, e.g. Facebook graph api profile pics.
* If a cached image exists, the completion block is called once with the cached image and again with the final image.
*/
SDWebImageRefreshCached = 1 << 4
} SDWebImageOptions;
typedef void(^SDWebImageCompletedBlock)(UIImage *image, NSError *error, SDImageCacheType cacheType);

15
SDWebImage/SDWebImageManager.m
View File

@ -97,16 +97,21 @@
if (image)
{
completedBlock(image, nil, cacheType, YES);
@synchronized(self.runningOperations)
{
[self.runningOperations removeObject:operation];
if (!(options & SDWebImageRefreshCached)) {
@synchronized(self.runningOperations)
{
[self.runningOperations removeObject:operation];
}
}
}
else if (![self.delegate respondsToSelector:@selector(imageManager:shouldDownloadImageForURL:)] || [self.delegate imageManager:self shouldDownloadImageForURL:url])
if ((!image || options & SDWebImageRefreshCached) && (![self.delegate respondsToSelector:@selector(imageManager:shouldDownloadImageForURL:)] || [self.delegate imageManager:self shouldDownloadImageForURL:url]))
{
// download if no image or requested to refresh anyway, and download allowed by delegate
SDWebImageDownloaderOptions downloaderOptions = 0;
if (options & SDWebImageLowPriority) downloaderOptions |= SDWebImageDownloaderLowPriority;
if (options & SDWebImageProgressiveDownload) downloaderOptions |= SDWebImageDownloaderProgressiveDownload;
if (options & SDWebImageRefreshCached) downloaderOptions |= SDWebImageDownloaderEnableNSURLCache;
__block id<SDWebImageOperation> subOperation = [self.imageDownloader downloadImageWithURL:url options:downloaderOptions progress:progressBlock completed:^(UIImage *downloadedImage, NSData *data, NSError *error, BOOL finished)
{
if (weakOperation.cancelled)
@ -167,7 +172,7 @@
}];
operation.cancelBlock = ^{[subOperation cancel];};
}
else
else if (!image)
{
// Image not in cache and download disallowed by delegate
completedBlock(nil, nil, SDImageCacheTypeNone, YES);