Metal 2.0 specs for the Engine?

Where i can i found infos about the max specs for metal 2.0 for iphone?
About textures and so on. I only find for opengl es 3.1.

bump, I feel that metal 2 is more capable than open gl es 3.1 but I could be wrong. I would love some definitive info on this

I wish they would add something to check the material shader against the metal spec because right now I never know if the material shader I am compiling will render on the device or not - I have a good idea, i.e. you can’t go over 16 texture samplers, but sometimes my shaders still wont render on the device and I don’t know why. The mobile stat checker is no good because the metal spec is significantly different (more capable) than ES2.0. There is the iOS preview view but its still not a perfect solution because you can’t build lighting and stuff when using that preview view.