iOS8 Photos Framework: How to get the name(or filename) of a PHAsset?

I know the question has already been answered, but I figured I would provide another option:

extension PHAsset {

    var originalFilename: String? {

        var fname:String?

        if #available(iOS 9.0, *) {
            let resources = PHAssetResource.assetResources(for: self)
            if let resource = resources.first {
                fname = resource.originalFilename
            }
        }

        if fname == nil {
            // this is an undocumented workaround that works as of iOS 9.1
            fname = self.value(forKey: "filename") as? String
        }

        return fname
    }
}

If you want to get the image name (for example name of last photo in Photos) like IMG_XXX.JPG, you can try this:

PHAsset *asset = nil;
PHFetchOptions *fetchOptions = [[PHFetchOptions alloc] init];
fetchOptions.sortDescriptors = @[[NSSortDescriptor sortDescriptorWithKey:@"creationDate" ascending:YES]];
PHFetchResult *fetchResult = [PHAsset fetchAssetsWithMediaType:PHAssetMediaTypeImage options:fetchOptions];
if (fetchResult != nil && fetchResult.count > 0) {
    // get last photo from Photos
    asset = [fetchResult lastObject];
}

if (asset) {
    // get photo info from this asset
    PHImageRequestOptions * imageRequestOptions = [[PHImageRequestOptions alloc] init];
    imageRequestOptions.synchronous = YES;
    [[PHImageManager defaultManager]
             requestImageDataForAsset:asset
                            options:imageRequestOptions
                      resultHandler:^(NSData *imageData, NSString *dataUTI,
                                      UIImageOrientation orientation, 
                                      NSDictionary *info) 
     {
          NSLog(@"info = %@", info);
          if ([info objectForKey:@"PHImageFileURLKey"]) {
               // path looks like this - 
               // file:///var/mobile/Media/DCIM/###APPLE/IMG_####.JPG
               NSURL *path = [info objectForKey:@"PHImageFileURLKey"];
     }                                            
    }];
}

Hope it helps.

In Swift the code will look like this

PHImageManager.defaultManager().requestImageDataForAsset(asset, options: PHImageRequestOptions(), resultHandler:
{
    (imagedata, dataUTI, orientation, info) in
    if info!.keys.contains(NSString(string: "PHImageFileURLKey"))
    {
        let path = info![NSString(string: "PHImageFileURLKey")] as! NSURL
    }
})

Swift 4:

    let fetchResult = PHAsset.fetchAssets(with: .image, options: nil)
    if fetchResult.count > 0 {
        if let asset = fetchResult.firstObject {
            let date = asset.creationDate ?? Date()
            print("Creation date: \(date)")
            PHImageManager.default().requestImageData(for: asset, options: PHImageRequestOptions(),
                resultHandler: { (imagedata, dataUTI, orientation, info) in
                    if let info = info {
                        if info.keys.contains(NSString(string: "PHImageFileURLKey")) {
                            if let path = info[NSString(string: "PHImageFileURLKey")] as? NSURL {
                                print(path)
                            }
                        }
                    }
            })
        }
    }

One more option is:

[asset valueForKey:@"filename"]

The "legality" of this is up to you to decide.

Easiest solution for iOS 9+ in Swift 4 (based on skims answer):

extension PHAsset {
    var originalFilename: String? {
        return PHAssetResource.assetResources(for: self).first?.originalFilename
    }
}

For Swift

asset?.value(forKey: "filename") as? String

For objective C

[asset valueForKey:@"filename"]