i'm beginner.i have a problem about SDURLCache and AFNetwoking.my code:
first,i setting sdurlcache in my appdelegate.m
self.cache = [[SDURLCache alloc] initWithMemoryCapacity:1024*1024 // 1 MB mem cache
diskCapacity:1024*1024*5 // 5 MB disk cache
diskPath:[SDURLCache defaultCachePath]];
self.cache.ignoreMemoryOnlyStoragePolicy = YES;
[NSURLCache setSharedURLCache:self.cache];
second,i used AFNetwoking+UIImageView in my tableCell:
[cell.Image setImageWithURL:url placeholderImage:[UIImage imageNamed:#"zhanweiSmall.png"]];
But picture not cache.if network is invalid,picture don't show
If you are using IOS5 or above NSURLCache automatically saves responses to disk. So you don't need SDURLCache. See Peter's blog post for more info.
http://petersteinberger.com/blog/2012/nsurlcache-uses-a-disk-cache-as-of-ios5/
Related
my code looks like
if([[self cache] isEqualToNumber:[[NSNumber alloc] initWithInt:1]])
{
[[NSURLCache sharedURLCache] setDiskCapacity:4 * 1024 * 1024];
[[NSURLCache sharedURLCache] setMemoryCapacity:32 * 1024 * 1024];
[self setRequestObj:[NSURLRequest requestWithURL:loadUrl cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:60.0]];
}
else [self setRequestObj:[NSURLRequest requestWithURL:loadUrl cachePolicy:NSURLRequestReloadIgnoringLocalCacheData timeoutInterval:60.0]];
My else part does not work. Why is my UIWebView not ignoring my local cache?
Every time I visited a testsite my app does not load from the original source. He only load the index.html but the linked images only at first visit.
What's my issue?
The NSURLRequestReloadIgnoringLocalCacheData flag affects only that one request, not future requests. So this works as expected. If you want to disable other caching, the only way I know of to do that is by implementing an NSURLProtocol that intercepts the HTTP/HTTPS requests, modifies them in an identifiable way (e.g. adding a custom header), and then re-sends them. This is not for the faint of heart.
You're probably better off just purging the cache: How to clear UIWebView cache?
I had the same problem I think it is probably a UIWebView bug. Because after I changed it WKWebView, NSURLRequestReloadIgnoringLocalCacheData works!
I am using AFNetworking 3.0's UIImageView+AFNetworking to display images in a UICollectionView.
However as I keep scrolling, the memory usage of my app keeps growing forever. I used Instruments Allocations tool and am able to narrow down the issue to CG Raster Data which keeps growing for every image which is loaded. Looking at the details of the CG Raster Data, The responsible caller is cgdataprovidercreatewithcopyofdata and responsible library is CoreGraphics. For each cell loaded, a 240 KB memory is wasted.
There are a lot of similar issues on stack overflow but none really help/have a solution.
I thought this might be due to cache, so I enabled following but didn't help at all:
NSURLCache * sharedCache = [[NSURLCache alloc] initWithMemoryCapacity:0 diskCapacity:10 * 1024 diskPath:nil];
[NSURLCache setSharedURLCache:sharedCache];
I tried wrapping the setImageWithURLRequest inside an autoreleasepool but didn't help.
I tried searching for cgdataprovidercreatewithcopyofdata in the entire app but I find no hits in my app or the afnetworking. However if I remove the loading of the image, then I don't see this issue.
Also if I remove the setting of the image inside the completion handler, the memory still grows. Meaning that setImageWithURLRequest itself is the culprit and not the setting of the image inside the completion handler.
I have been struggling with this for a while, any help would be appreciated!
Here's my code for the setting of image:
[cell.thumbnail cancelImageDownloadTask];
__weak UIImageView *weakImageView = cell.thumbnail;
#autoreleasepool {
[cell.thumbnail setImageWithURLRequest:[NSURLRequest requestWithURL:[NSURL URLWithString:#"http://myurl/image.png"]]
placeholderImage:[UIImage imageNamed:#"placeholder.png"]
success:^(NSURLRequest *request, NSHTTPURLResponse *response, UIImage *image) {
UIImageView *strongImageView = weakImageView; // make local strong reference to protect against race conditions
if (!strongImageView) return;
[UIView transitionWithView:strongImageView
duration:0.3
options:UIViewAnimationOptionTransitionCrossDissolve
animations:^{
strongImageView.image = image;
}
completion:NULL];
}
failure:NULL];
Here's screenshots from instruments:
I used #ajay gabani response to use SDWebImage instead of AFNetworking's ImageView.
In SDWebImage it at least provided a way to clear the cache plus you can control whether the image is cached in disk or only memory.
I set the maxMemoryCountLimit to 10 but it doesn't seem to do much in my testing:
SDImageCache *imageCache = [SDImageCache sharedImageCache];
imageCache.maxMemoryCountLimit=10;
I clear the cache every few seconds:
[NSTimer scheduledTimerWithTimeInterval:5.0 target:self selector:#selector(simulateMemoryWarning) userInfo:nil repeats:YES];
- (void)simulateMemoryWarning{
[[NSNotificationCenter defaultCenter] postNotificationName:UIApplicationDidReceiveMemoryWarningNotification object:nil];
SDImageCache *imageCache = [SDImageCache sharedImageCache];
NSLog(#"Simulated");
[imageCache clearMemory];
[imageCache clearDisk];
}
I am developing a content display app in which there is a table view and a detail view corresponding to each row in the table.
There are 12 categories in which content is loaded.
I have completed the app and it is working fine. Now I need to manage memory consumption for cache as I am receiving a warning at run time. I am using AFNetowking lib for caching.
There is no problem in functioning of the app. I just need to do some memory management and apply the code.
I am trying to allocate some particular memory and disk apace for each category.
following is the code that i am using to allocate ram and disk size for each category.
NSURLCache *sharedCache = [[NSURLCache alloc] initWithMemoryCapacity:15 * 512 * 1024
diskCapacity:10 * 1024 * 1024
diskPath:nil];
[NSURLCache setSharedURLCache:sharedCache];
xcode version : 6.1
taget ios version : 6.0
app : universal
I think the recommendation is to not set the size of the cache. The system should take care of that.
I would generally use a common NSCache, and just store data packets based on the URL. And then convert the data back into any image/xml/text whatever I was expecting.
// This should reference an NSCache instance
_contentCache = [[NSCache alloc] init];
// create a key for the request.
cacheKey = [NSString stringWithFormat:#"%#|%#",uri,body];
NSData *cacheData = [_contentCache objectForKey:cacheKey];
// if its in the cache, just return it.
if (cacheData) {
return cacheData;
}
// Request the data here and return it.
_contentCache is defined in the AppDelegate. So that I can reference it easily from across the app.
- (id) init {
_appDelegate = (AppDelegate *)[[UIApplication sharedApplication] delegate];
_contentCache = [_appDelegate contentCache];
return self;
}
I've posted my class to GitHub. Its not complete, but its useable.
postmaster - GitHub
At this point I'm really fed up. It's been nearly a week now trying to solve this issue so I can move ahead. I've read multiple threads and done multiple searches in regards to my slow loading choppy UICollectionView.
I've tried to do this without any libraries as well as with SDWebImage and AFNetwork. It still doesn't fix things. Images loading isn't really a problem. The problem arrives when I scroll to cells that aren't currently showing on the screen.
As of now I've deleted all the code and all traces of any libraries and would like to get help in order to implement this properly. I've made about 2 posts on this already and this would be my third attempt coming from a different angle.
Information
My backend data is stored on Parse.com
I have access to currently loaded objects by calling [self objects]
My cellForItemAtIndex is a modified version that also returns the current object of an index.
From what I understand in my cellForItemAtIndex I need to check for an image, if there isn't one I need to download one on background thread and set it so it shows in the cell, then store a copy of it in cache so that if the associated cell goes off screen when I do scroll back to it I can use the cached image rather than downloading it again.
My custom parse collectionViewController gives me all the boiler plate code I need to get access to next set of objects, current loaded objects, pagination, pull to refresh etc. I really just need to get this collection view sorted. I never needed to do any of this with my tableview of a previous app which had much more images. It's really frustrating spending a whole day trying to solve an issue and getting no where.
This is my current collectionView cellForItemAtIndex:
-(UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath object:(PFObject *)object
{
static NSString *CellIdentifier = #"Cell";
VAGGarmentCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier: CellIdentifier forIndexPath:indexPath];
// check for image
// if there is a cached one use that
// if not then download one on background thread
// set my cells image view with that image
// cache image for re-use.
// PFFile *userImageFile = object[#"image"];
[[cell title] setText:[object valueForKey:#"title"]]; //title set
[[cell price] setText:[NSString stringWithFormat: #"£%#", [object valueForKey:#"price"]]]; //price set
return cell;
}
I am also using a custom collectionViewCell:
#interface VAGGarmentCell : UICollectionViewCell
#property (weak, nonatomic) IBOutlet UIImageView *imageView;
#property (weak, nonatomic) IBOutlet UITextView *title;
#property (weak, nonatomic) IBOutlet UILabel *price;
#property (weak, nonatomic) IBOutlet UIActivityIndicatorView *activityIndicator;
#end
If there's any more information you'd like please ask. I'd just like a clear example in code of how to do this correctly, if it still doesn't work for me then I guess there is something wrong some where within my code.
I'm going to continue reading through various threads and resources I've come across in the last few days. I can say one benefit in this experience is that I have a better understanding of threads and lazy loading but it is still very frustrated that I have made any progress with my actual app.
Incase you wondered here is my previous post: In a UICollectionView how can I preload data outside of the cellForItemAtIndexPath to use within it?
I'd either like to do this quick and manually or using the AFNetwork as that didn't cause any errors or need hacks like SDWebImage did.
Hope you can help
Kind regards.
You can make use of the internal cache used by NSURLConnection for this.
-(UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
{
VAGGarmentCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:#"VAGGarmentCell" forIndexPath:indexPath];
//Standard code for initialisation.
NSURL *url; //The image URL goes here.
NSURLRequest *request = [NSURLRequest requestWithURL:url cachePolicy:NSURLRequestReturnCacheDataElseLoad timeoutInterval:5.0]; //timeout can be adjusted
[NSURLConnection sendAsynchronousRequest:request queue:[NSOperationQueue mainQueue] completionHandler:^(NSURLResponse *response, NSData *data, NSError *connectionError)
{
if (!connectionError)
{
UIImage *image = [UIImage imageWithData:data];
//Add image as subview here.
}
}];
.
.
return cell;
}
This is for a table view, but same concept basically. I had the same issue you were having. I had to check for a cached image, if not, retrieve it from a server. The main thing to watch out for is when you retrieve the image back, you have to update it in the collection view on the main thread. You also want to check if the cell is still visible on the screen. Here is my code as an example. teamMember is a dictionary and #"avatar" is the key which contains the URL of the user's image. TeamCommitsCell is my custom cell.
// if user has an avatar
if (![teamMember[#"avatar"] isEqualToString:#""]) {
// check for cached image, use if it exists
UIImage *cachedImage = [self.imageCache objectForKey:teamMember[#"avatar"]];
if (cachedImage) {
cell.memberImage.image = cachedImage;
}
//else retrieve the image from server
else {
NSURL *imageURL = [NSURL URLWithString:teamMember[#"avatar"]];
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_BACKGROUND, 0), ^{
NSData *imageData = [NSData dataWithContentsOfURL:imageURL];
// if valid data, create UIImage
if (imageData) {
UIImage *image = [UIImage imageWithData:imageData];
// if valid image, update in tableview asynch
if (image) {
dispatch_async(dispatch_get_main_queue(), ^{
TeamCommitsCell *updateCell = (id)[tableView cellForRowAtIndexPath:indexPath];
// if valid cell, display image and add to cache
if (updateCell) {
updateCell.memberImage.image = image;
[self.imageCache setObject:image forKey:teamMember[#"avatar"]];
}
});
}
}
});
}
}
NSURLCache is iOS's solution to caching retrieved data, including images. In your AppDelegate, initialize the shared cache via:
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
NSURLCache *cache = [[NSURLCache alloc] initWithMemoryCapacity:8 * 1024 * 1024
diskCapacity:20 * 1024 * 1024
diskPath:nil];
[NSURLCache setSharedURLCache:cache];
return YES;
}
-(void)applicationDidReceiveMemoryWarning:(UIApplication *)application {
[[NSURLCache sharedURLCache] removeAllCachedResponses];
}
Then use AFNetworking's UIImageView category to set the image using:
[imageView setImageWithURL:myImagesURL placeholderImage:nil];
This has proven to load images the second time around incredibly faster. If you are worried about loading images faster for the first time, you will have to create a way to determine when and how many images you want to load ahead of time. It is very common to load data using paging. If you are using paging and still are having trouble, consider using AFNetworking's:
- (void)setImageWithURLRequest:(NSURLRequest *)urlRequest
placeholderImage:(UIImage *)placeholderImage
success:(void (^)(NSURLRequest *request, NSHTTPURLResponse *response, UIImage *image))success
failure:(void (^)(NSURLRequest *request, NSHTTPURLResponse *response, NSError *error))failure;
This way you can create an array of UIImages and using this method to return the images for each cell before dequeuing the cell. So in this case you would have two parallel arrays; one holding your data and the other holding corresponding UIImages. Memory management will eventually get out of hand so keep that in mind. If someone scrolls quickly to the bottom of the available cells, there is honestly not much else you can do since the data depends on the network connection of the user.
After several days the issue was my images were far too large. I had to resize them and this instantly solved my issue.
I literally narrowed things down and checked my images to find they were not being resized by the method I thought was resizing them. This is why I need to get myself used to testing.
I learnt a lot about GCD and caching in the past few days but this issue could have been solved much earlier.
We all know about the mysterious behind-the-scenes caching mechanism of UIImage's imageNamed: method. In Apple's UIImage Class Reference it says:
In low-memory situations, image data may be purged from a UIImage object to free up memory on the system. This purging behavior affects only the image data stored internally by the UIImage object and not the object itself. When you attempt to draw an image whose data has been purged, the image object automatically reloads the data from its original file. This extra load step, however, may incur a small performance penalty.
In fact, image data will not be "purged from a UIImage object to free up memory on the system" as the documentation suggests, however. Instead, the app receives memory warnings until it quits "due to memory pressure".
EDIT: When using the conventional image file references in your Xcode project, the UIImage caching works fine. It's just when you transition to Asset Catalogs that the memory is never released.
I implemented a UIScrollView with a couple of UIImageViews to scroll through a long list of images. When scrolling, the next images are being loaded and assigned to the UIImageView's image property, removing the strong link to the UIImage it has been holding previously.
Because of imageNamed:'s caching mechanism, I quickly run out of memory, though, and the app terminates with around 170 MB memory allocated.
Of course there are plenty of interesting solutions around to implement custom caching mechanisms, including overriding the imageNamed: class method in a category. Often, the class method imageWithContentOfFile: that does not cache the image data is used instead, as even suggested by Apple developers at the WWDC 2011.
These solutions work fine for regular image files, although you have to get the path and file extension which is not quite as elegant as I would like it to be.
I am using the new Asset Catalogs introduced in Xcode 5, though, to make use of the mechanisms of conditionally loading images depending on the device and the efficient image file storage. As of now, there seems to be no straight forward way to load an image from an Asset Catalog without using imageNamed:, unless I am missing an obvious solution.
Do you guys have figured out a UIImage caching mechanism with Asset Catalogs?
I would like to implement a category on UIImage similar to the following:
static NSCache *_cache = nil;
#implementation UIImage (Caching)
+ (UIImage *)cachedImageNamed:(NSString *)name {
if (!_cache) _cache = [[NSCache alloc] init];
if (![_cache objectForKey:name]) {
UIImage *image = ???; // load image from Asset Catalog without internal caching mechanism
[_cache setObject:image forKey:name];
}
return [_cache objectForKey:name];
}
+ (void)emptyCache {
[_cache removeAllObjects];
}
#end
Even better would of course be a way to have more control over UIImage's internal cache and the possibility to purge image data on low memory conditions as described in the documentation when using Asset Catalogs.
Thank you for reading and I look forward to your ideas!
UPDATE: Cache eviction works fines (at least since iOS 8.3).
I am running into the same issue (iOS 7.1.1) and I kind of though that #Lukas might be right
There is a high probability that the mistake is not inside Apple's ... caching but in your .. code.
Therefore I have written a very simple Test App (view full source below) where I still see the issue. If you see anything wrong with it, please let the me know about it. I know that it really depends on the image sizes. I only see the issue on an iPad Retina.
#interface ViewController ()
#property (nonatomic, strong) UIImageView *imageView;
#property (nonatomic, strong) NSArray *imageArray;
#property (nonatomic) NSUInteger counter;
#end
#implementation ViewController
- (void)viewDidLoad
{
[super viewDidLoad];
self.imageArray = #[#"img1", ... , #"img568"];
self.counter = 0;
UIImage *image = [UIImage imageNamed:[self.imageArray objectAtIndex:self.counter]];
self.imageView = [[UIImageView alloc] initWithImage: image];
[self.view addSubview: self.imageView];
[self performSelector:#selector(loadNextImage) withObject:nil afterDelay:1];
}
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
NSLog(#"WARN: %s", __PRETTY_FUNCTION__);
}
- (void)loadNextImage{
self.counter++;
if (self.counter < [self.imageArray count])
{
NSLog(#"INFO: %s - %lu - %#",
__PRETTY_FUNCTION__,
(unsigned long)self.counter,
[self.imageArray objectAtIndex:self.counter]);
UIImage *image = [UIImage imageNamed:[self.imageArray objectAtIndex:self.counter]];
self.imageView.frame = CGRectMake(0, 0, image.size.width, image.size.height);
[self.imageView setImage:image];
[self performSelector:#selector(loadNextImage) withObject:nil afterDelay:0.2];
} else
{
NSLog(#"INFO: %s %#", __PRETTY_FUNCTION__, #"finished");
[self.imageView removeFromSuperview];
}
}
#end
Inplace Implementation
I wrote some code to keep the image asset but load it with imageWithData: or imageWithContentsOfFile: use xcassets without imageNamed to prevent memory problems?