Access Asset Catalog pathForResource

Question

It appears that:

[[NSBundle mainBundle] pathForResource:@\"name\" ofType:@\"png\"];

Does not return anything for assets that are inside the Ima

Answer 1

Although there is a Contents.json file (see below) associated with each item in xcassets that contains the filenames of that item's images, it does not appear to be accessible at the filesystem level. All images are placed in a single filesystem folder upon compilation. The json file is auto-generated and should not be edited, but it does provide a template for a workaround.

Name each file with a consistent suffix to match the corresponding idiom, scale and subtype appearing in the json file. This requires manual work by selecting the 'Show in Finder' option for each asset and renaming each file, but once completed, you can then use pathForResource in combination with a function to add the appropriate suffix to the base asset name to retrieve the appropriately-sized image.

Sample code to retrieve path:

NSString *imageName = @"Add to Cart";
NSString *imageSuffix = [self someMethodThatDeterminesSuffix]; // Example: "-iphone-2x-retina4"
NSString *imagePath = [[NSBundle mainBundle] pathForResource:[NSString stringWithFormat:@"%@%@", imageName, imageSuffix] ofType:@"png"];

Example Contents.json file for the "Add to Cart" image asset:

{
  "images" : [
    {
      "idiom" : "iphone",
      "scale" : "1x",
      "filename" : "Add to Cart-iphone-1x.png"
    },
    {
      "idiom" : "iphone",
      "scale" : "2x",
      "filename" : "Add to Cart-iphone-2x.png"
    },
    {
      "idiom" : "iphone",
      "filename" : "Add to Cart-iphone-2x-retina4.png",
      "subtype" : "retina4",
      "scale" : "2x"
    }
  ],
  "info" : {
    "version" : 1,
    "author" : "xcode"
  }
}

Answer 2

I wanted to access some vector assets for creating UNNotificationAttachment with local resources so I came up with this helper class. It basically just gets image from assets, saves its data to disk and return file URL. I hope that helps someone.

import UIKit

class AssetExtractor {

    static func createLocalUrl(forImageNamed name: String) -> URL? {

        let fileManager = FileManager.default
        let cacheDirectory = fileManager.urls(for: .cachesDirectory, in: .userDomainMask)[0]
        let url = cacheDirectory.appendingPathComponent("\(name).png")

        guard fileManager.fileExists(atPath: url.path) else {
            guard
                let image = UIImage(named: name),
                let data = UIImagePNGRepresentation(image)
            else { return nil }

            fileManager.createFile(atPath: url.path, contents: data, attributes: nil)
            return url
        }

        return url
    }

}

Answer 3

For launch images and application icons in particular, the image paths are available via the UILaunchImages and CFBundleIcons Info.plist keys respectively. It appears those images are generated individually and the Info.plist values updated during the app build when using asset catalogs (and if not, those keys are written to directly by the Xcode UI). You might have to write some code to figure out the correct sub-dictionary to use, but the images are available separately and you can avoid using imageNamed in that case.

Answer 4

Try using the image name as determined in the "Compile asset catalog" step. You'll find this in the build output. Be sure to expand the transcript - you should see something like this:

/* com.apple.actool.compilation-results */
/path/to/Debug-iphonesimulator/Your.app/LaunchImage-800-Portrait-736h@3x.png
/path/to/Debug-iphonesimulator/Your.app/LaunchImage-800-667h@2x.png
/path/to/Debug-iphonesimulator/Your.app/LaunchImage-700@2x.png
/path/to/Debug-iphonesimulator/Your.app/LaunchImage-700-568h@2x.png
/path/to/Debug-iphonesimulator/Your.app/LaunchImage-700-Landscape~ipad.png
/path/to/Debug-iphonesimulator/Your.app/LaunchImage-700-Landscape@2x~ipad.png

Tested using +[UIImage imageNamed:] with Xcode 6.1.1.

Answer 5

Same problem, but I don't think we could access it via pathForResource:, except below:

UIImage* image = [UIImage imageNamed:@"name-in-asset-catalog"];

It has been clearly documented:

Each set in an asset catalog has a name. You can use that name to programmatically load any individual image contained in the set. To load an image, call the UIImage:imageNamed: method, passing the name of the set that contains the image.

I found that in the package of complied app, a file named "Assets.car" came out, and I think it's the entire images sets in my project, and should have been zipped or something.

Refer to Apple's documentation:

Xcode 5 provides different functionality for asset catalogs depending on the deployment target for your project:

• For all projects, individual images can be loaded using set names.
• For projects with a deployment target of iOS 7, Xcode compiles your asset catalogs into a runtime binary file format that reduces the download time for your app.

So that's it.

I'm also looking for a way that doesn't use imageNamed:, I don't want runtime to cache my images.

Answer 6

[UIImage imageWithContentsOfFile:[NSString stringWithFormat:@"%@/%@.png", [[NSBundle mainBundle] resourcePath], imgName]];

imgName: the name of Image set, not caring the true name of the image in Image set.