CODEWITHSUNDEEP
cocoaswiftcachingnsimage
udondan
udondan

Reputation: 59989

How to NOT cache an NSImage loaded byReferencingURL

How would I load an NSImage from URL without caching it? It should always be re-loaded from the remote source. But even if I am not connected to the internet, I end up with a valid image. Setting the cache mode to the already loaded image does not have any effect.

let url = NSURL(string: "http://thecybershadow.net/misc/stackoverflow.png")
let img = NSImage(byReferencingURL: url!)
img.cacheMode = NSImageCacheMode.Never
NSLog("Found image with size \(img.size)")

When I run this snippet in a playground, it actually never caches, even if I set NSImageCacheMode.Always.

But when I run this snippet in my application, it always returns a valid image, even if I'm not connected to the internet.

I know I could simply use a cache buster parameter with a random number or timestamp. But this is a theoretical question and I'm interested in how to prevent caching in the first place.

Upvotes: 0

Views: 926

Answers (1)

owenfi
owenfi

Reputation: 2631

Ran into this issue in objc as well (I think, trying out this fix now).

I assume you can work around it thusly:

NSString *imgURL = @"http://thecybershadow.net/misc/stackoverflow.png";
NSURL *u = [NSURL URLWithString:imgURL];

NSError *error;
NSData *d = [NSData dataWithContentsOfURL:u
                                  options:NSDataReadingUncached
                                    error:&error];
NSImage *image = [[NSImage alloc] initWithData:d];

I believe that will load from the network resource every time.

I might take a crack at swift after I do some testing to figure out if it actually works.

Upvotes: 1

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