Features currently not supported by Unity iOS

Graphics

• DXT texture compression is not supported; use PVRTC formats instead. Please see the Texture2D Component page for more information.
• Rectangular textures can not be compressed to PVRTC formats.
• Movie Textures are not supported; use a full-screen streaming playback instead. Please see the Movie playback page for more information.

Scripting

• Dynamic features like Duck Typing are not supported. Use #pragma strict for your scripts to force the compiler to report dynamic features as errors.
• Video streaming via WWW class is not supported.
• FTP support by WWW class is limited.

Features Restricted to Unity iOS Pro License

• Splash-screen customization

External Libraries

It is recommended to minimize your references to external libraries, because 1 MB of .NET CIL code roughly translates to 3–4 MB of ARM code. For example, if your application references System.dll and System.Xml.dll then it means additional 6 MB of ARM code if stripping is not used. At some point application will reach limit when linker will have troubles linking the code. If you care a lot about application size you might find C# a more suitable language for your code as is has less dependencies than JavaScript.