Unity, Trail renderer gone black on IOS

Add a trail renderer to the object, use the legacy shaders/transparent/diffuse, and turn the color into white translucent. The effect is right in the editor, but the real machine test turns black on iOS. Then look at Trailrenderer's document (http://docs.unity3d.com/Manual/class-TrailRenderer.html), which reads:

Trail renderers should use a material, which has a particle Shader.

Then use Mobile/particle/alpha blended, and add a white translucent map up, and then the iOS test, the effect is normal.

Unity, Trail renderer gone black on IOS