confusion in data storage into nscache

Question

i know that im doing a mistake here coz i cant run the project im trying to build and also what im trying to do here is to get a parsed data from an xml then save it into a an nsdata and then put all those data into a cache so when i run my project it doesnt always load for the data.

@implementation ViewController
{    
    NSCache *myCache;    
}


- (void)viewDidLoad
{    
    myCache = [[NSCache alloc] init];
}

//saving data into cache
NSString *imageURL = [currentData.imageLink];
NSURL *url = [NSURL URLWithString:imageURL];
NSData *data = [NSData dataWithContentsOfURL:url];
data = [imagesCache objectForKey:@"KEY"];
[imagesCache setObject:imageLinks forKey:@"KEY"];

Your are having problem when you fetch the data from NSCache ? — Guilherme Torres Castro, Aug 19 '13 at 16:53
You probably want to save the NSData (or better, the resulting UIImage) in the cache, not the URL. And are you just caching for the session, or did you need a persistent cache? — Rob, Aug 19 '13 at 16:54
i would like to save the data in tha nsdata to the cache and then give the data into uiImage to show the images in it which. — Ace Munim, Aug 19 '13 at 16:57
and do i need to do cell.imageShow.image = [UIImage imageWithData:data]; — Ace Munim, Aug 19 '13 at 17:00

score 1 · Accepted Answer · edited Dec 04 '13 at 06:59

A few things:

Data downloads should be done on a background thread.
It's best to have your own object in the cache, and that object should download the image and cache both the image and save the image to disk. When the cache gets purged you should remove the image and then reload from disk if required.

This code:

NSData *data = [NSData dataWithContentsOfURL:url];
data = [imagesCache objectForKey:@"KEY"];
[imagesCache setObject:[NSData dataWithContentsOfURL:url] forKey:@"KEY"];

Downloads the date, throws it away and replaces it with whatever was in the cache and then updates the cache with something else. It should be more like:

[imagesCache setObject:imageLinks forKey:@"KEY"];

For point 2 your objects should confirm to NSDiscardableContent.

sorry for being a noob here, but what would i do to put the data that is in the NSData to the NSCache object, coz the NSData's object has the data that i fetch from the xml. coz as i read from ur reply, the code i wrote doesn't do any data saving in the cache i made. — Ace Munim, Aug 19 '13 at 18:10

score -1 · Answer 2 · answered Aug 19 '13 at 16:59

-1

NSCache does not save the data in disk, only in memory.

And it may automatically remove the data stored in it, if needed.

For more information you take a look here

answered Aug 19 '13 at 16:59

Guilherme Torres Castro

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yes i know that.i wanted to save it temporarily. i been reading stuff about nscache before posted that here. – Ace Munim Aug 19 '13 at 17:01

confusion in data storage into nscache

2 Answers2