Unity官网针对IOS开发有比较好的建议，我总结了翻译如下，后面附上原文。
- 尽量控制定点数量（注意所谓顶点不是建模时的顶点，而是引擎渲染时的顶点。例如，模型一个顶点如果设置了2个法向，那么对引擎来说就是2个顶点） ：
- 对Iphone3或更高设备，每帧渲染的顶点不超过4万个
- 对更早的设备，每帧渲染的顶点不超过1万个
- 场景所用的材质尽量减少。即使是不同的物件，也尽量采用同一个材质。
- 将固定的场景物件设置为静态（static）。
- 尽量使用PVRTC（这是Apple推荐的一种格式）纹理，不行的话，也尽量用16位纹理取代32位的。
- 不要在shader中使用multi-pass，通过用混合或者像素shader来合并不同的纹理以达到相同效果。
- 如果自行编写shader，尽量避免使用浮点数。下面是建议的类型：
- fixed/lowp——适用于颜色，光照等
- half/mediump——适用于纹理UV
- float/highp——避免在像素shader里使用，可以在顶点shader里面用于计算顶点位置
- 在像素shader中尽量少用复杂的数学计算，例如幂函数、三角函数等。
- 没必要的话不要使用像素光照（Pixel Lights）
- 不要使用动态光照，用烘焙的lightmap
- 不要使用alpha测试，用alpha混合来代替
- 不要使用雾
- 大场景中使用Occlusion culling来削减不可见区域。关卡设计时考虑到实施 Occlusion culling 的便利性
- 使用sky box 来实现远景
原文如下：
- Keep vertex count below:
- 40K per frame when targeting iPhone 3GS and newer devices (with SGX GPU)
- 10K per frame when targeting older devices (with MBX GPU)
- Keep the number of different materials per scene low - share as many materials between different objects as possible.
- Set Static property on a non-moving objects to allow internal optimizations.
- Use PVRTC formats for textures when possible, otherwise choose 16bit textures over 32bit.
- Use combiners or pixel shaders to mix several textures per fragment instead of multi-pass approach.
- If writing custom shaders, always use smallest possible floating-point types:
- fixed / lowp -- perfect for color, lighting information and normals,
- half / mediump -- for texture UV coordinates,
- float / highp -- avoid in pixel shaders, fine to use in vertex shader for vertex position calculations.
- Minimize use of complex mathematical operations such as pow, sin, cos etc in pixel shaders.
- Do not use Pixel Lights when it is not necessary -- choose to have only a single (preferably directional) pixel light affecting your geometry.
- Do not use dynamic lights when it is not necessary -- choose baking lighting instead.
- Choose to use less textures per fragment.
- Avoid alpha-testing, choose alpha-blending instead.
- Do not use fog when it is not necessary.
- Learn benefits of Occlusion culling and use it to reduce amount of visible geometry and draw-calls in case of complex static scenes with lots of occlusion. Plan your levels to benefit from Occlusion culling.
- Use skyboxes to "fake" distant geometry.