First time to use AFNetworking. When I use it to download/reload image for my collectionView with setImageWithURLRequest:request method, I found the images could be downloaded, but never load from the cached image.
Well, I searched internet before asking this question, most of them said to use setImageWithURLRequest:request and it has a cache policy for the NSURLRequest I could configure before. I configure the policy as NSURLRequestReturnCacheDataElseLoad, it means use the cached data first otherwise re-download it if I understand correctly. And they also said I could check the response == nil to know if cached image is used. I also set the cache capacity in AppDelegate didFinishLaunching, though my image is roughly 50KB.
However it never happened, the response is always has a value in my case. Please advice what I am missing here?
AppDelegate
NSURLCache *sharedCache = [[NSURLCache alloc] initWithMemoryCapacity:20 * 1024 * 1024
diskCapacity:200 * 1024 * 1024
directoryURL:nil];
[NSURLCache setSharedURLCache:sharedCache];
The code snipper for download image
- (void)setupThumbnailImage {
__weak typeof(self) weakSelf = self;
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
NSURL *url = [NSURL URLWithString:weakSelf.video.thumbnailImageName];
NSURLRequest *request = [NSURLRequest requestWithURL:url cachePolicy:NSURLRequestReturnCacheDataElseLoad timeoutInterval:60];
[weakSelf.videoImageView setImageWithURLRequest:request placeholderImage:nil success:^(NSURLRequest * _Nonnull request, NSHTTPURLResponse * _Nullable response, UIImage * _Nonnull image) {
dispatch_async(dispatch_get_main_queue(), ^{
if (!response) {
weakSelf.videoImageView.image = image;
NSLog(@"use cache image ");
} else {
weakSelf.videoImageView.image = image;
NSLog(@"redownload image ");
}
});
} failure:^(NSURLRequest * _Nonnull request, NSHTTPURLResponse * _Nullable response, NSError * _Nonnull error) {
NSLog(@"Error: %@", error.localizedDescription);
}];
});
}
Update
Per Larme's comment, I did 2 test. First I put a break point on line 97 UIImage *cachedImage = [imageCache imageforRequest:urlRequest withAdditionalIdentifier:nil]; in file "UIImageView+AFNetworking.h".
- Use
NSURLRequestReturnCacheDataDontLoadand turn off network(offline mode).
Result: In debug console, I could see the cachedImage is nil. Then it try to use network to download the image. And an error fired as no network available.
Task <8A1D55F5-F884-4FEC-B7DF-756BD0BB2B34>.<6> HTTP load failed, 0/0 bytes (error code: -1009 [1:50]) Error Domain=NSURLErrorDomain Code=-1009 "The Internet connection appears to be offline."
- use
NSURLRequestReturnCacheDataElseLoad, and put my method for downloading image intoviewDidAppear, then do a VC switch/switch back.
Result: this method fired again, and this time it used cache image because code step over into if (cachedImage) statement and also NSLog(@"use cache image "); is printed out.
So in-memory cache image works. Current problem is in-disk cache image, when the app is closed and reopen, the method try to use the network to re-download images instead loading it from cache images.
Next, as larme'spoint, I'd like to dig into AFNetworking code to find out what URL path is actually used for their default cache image. Alternatively, I could write an in-disk image cache to not use AFNetworking image cache.
