Hi All,
Thank you for taking the time to read this post 
I’ve searched the forum and seem similar questions asked before, but I couldn’t quite find the answer to my issues. So I would like to ask for your input if you don’t mind:
I am using Unity 3.1 on OSX to create a game for iOS. I have around 2000 images in jpg or png format, the game will load around 10-20 images into the game depend on user’s action, and as the game progresses, unload existing images and load new images. It’s very similar to an image album.
The problem is - the game keep getting unloaded by iOS because it use too much memory.
I attempt to clean up unused Texture2D by using Texture2D.DestroyImmediate, and Resources.UnloadUnusedAssets whenever possible. I also make sure all references to the Texture2D are cleared.
I also try to reduce the runtime memory usage for the texture2d by using texture compression (PVRTC). I tried the following approaches:
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Use www or filestream to load into an Texture2D created without mipmap, then called the Texture2D.Compress function
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Import the images into the Resources with Unity editor, set the compression to PVRTC RGB 4 bits. And use Resources.Load when I need the texture
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similar to (1) above, but instead of png/jpg, I created .pvr with texturetool.
The problem are:
for (1) the Texture2D.Compress doesn’t seem to do anything at all on the iOS. I also tried to create Texture2D with TextureFormat.PVRTC_RGB4, but got an error “can’t create with compressed format” error.
for (2) this does use a lot less memory, but I can’t seem to unload the Texture2D at all.
for (3) I couldn’t find anyway to load the .pvr into Texture2D
So I am stuck at the moment. At the moment I have to stick with (1), but I could only work with 8 images at one time before the game run out of memory. I have a feeling I am missing some important clue. I would appreciate any advise here.
Thanks in advance!