Write png image metadata with pngcs

Hello,
I would like to write and read metadatas from PNG files, I’ve succefuly done the task with pngcs.dll library (1) but I’ve tryied to build the project for iOS and it doesn’t works, the library is not compatible, or I don’t know, the error message is this:

ArgumentException: The Assembly ICSharpCode.SharpZipLib is referenced by Pngcs ('Assets/Pngcs.dll'). But the dll is not allowed to be included or could not be found.
UnityEditor.AssemblyHelper.AddReferencedAssembliesRecurse (System.String assemblyPath, System.Collections.Generic.List`1 alreadyFoundAssemblies, System.String[] allAssemblyPaths, System.String[] foldersToSearch, System.Collections.Generic.Dictionary`2 cache, BuildTarget target) (at /Users/builduser/buildslave/unity/build/Editor/Mono/AssemblyHelper.cs:156)
UnityEditor.AssemblyHelper.FindAssembliesReferencedBy (System.String[] paths, System.String[] foldersToSearch, BuildTarget target) (at /Users/builduser/buildslave/unity/build/Editor/Mono/AssemblyHelper.cs:194)
UnityEditor.HostView:OnGUI()

And the build process (in Unity) terminate with this error message:

Error building Player: Extracting referenced dlls failed.

So, exists a way to make this dll works or another way to store/read metadatas from pngs?

Thanks

Can’t include dlls in iOS. You should be able to use the source code.