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.

Audio

• Ogg audio compression is not supported. Ogg audio will be automatically converted to MP3 when you switch to iOS platform in the Editor. Please see the AudioClip Component page for more information about audio support in Unity iOS.

Scripting

• OnMouseDown, OnMouseEnter, OnMouseOver, OnMouseExit, OnMouseDown, OnMouseUp, OnMouseDrag events are not supported.
• 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

• Static batching
• Video playback
• Splash-screen customization
• AssetBundles
• Code stripping
• .NET sockets

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.