Glow and Bloom Effects on iPhone

You can experiment with faking the bloom effect by using particle emmiter with addictive material for the particles, or few semi-transparent planes with additive material if you can predict when bloom effect should be happening. If you have fixed camera and a large bright area this solution might work. Adding a halo effect on the light may work as well.

Overall the Bloom effect and other post-processing effects require to have the Pixel Shader support(so it won't work on old iPhone models), and aren't cheap to render on the new iPhones as well(because it needs to render luma of each frame and then blur it and add to the result image). Hope this helps.

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Or you can use as well a lens flare with one or two layers with additive textures. So it stays always oriented at the camera and fades out when you're not looking at it.

Hi all as of mid-2014 with OpenGL ES 2 and OpenGL ES 3 Antialiasing, Bloom and Glow are feasible now.