Curve shader works fine on Windows, Android, macOS (Metal) but doesn't work properly for iOS (Metal)

Hey Guys,
I am using a curve shader from open source that works just fine on all the platforms, even with Metal API for macOS. It just doesn't seem to work properly for iOS devices using Metal API. I am using gamma color space so it's kind of necessary for me to use Metal and also the latest iOS and macOS has deprecated OpenGL API.
Can anyone tell if that really has to do something with the shader?
Here is my shader code.

Code (CSharp):

1. Shader "Custom/CurvedWorld" {
2.     Properties {
3.         // Diffuse texture
4.         _MainTex ("Base (RGB)", 2D) = "white" {}
5.         // Degree of curvature
6.         _Curvature ("Curvature", Float) = 0.001
7.     }
8.     SubShader {
9.         Tags { "RenderType"="Opaque" }
10.         LOD 200
11.         CGPROGRAM
12.         // Surface shader function is called surf, and vertex preprocessor function is called vert
13.         // addshadow used to add shadow collector and caster passes following vertex modification
14.         #pragma surface surf Lambert vertex:vert addshadow
15.         // Access the shaderlab properties
16.         uniform sampler2D _MainTex;
17.         uniform float _Curvature;
18.         // Basic input structure to the shader function
19.         // requires only a single set of UV texture mapping coordinates
20.         struct Input {
21.             float2 uv_MainTex;
22.         };
23.         // This is where the curvature is applied
24.         void vert( inout appdata_full v)
25.         {
26.             // Transform the vertex coordinates from model space into world space
27.             float4 vv = mul( _Object2World, v.vertex );
28.             // Now adjust the coordinates to be relative to the camera position
29.             vv.xyz -= _WorldSpaceCameraPos.xyz;
30.             // Reduce the y coordinate (i.e. lower the "height") of each vertex based
31.             // on the square of the distance from the camera in the z axis, multiplied
32.             // by the chosen curvature factor
33.             vv = float4( 0.0f, (vv.z * vv.z) * - _Curvature, 0.0f, 0.0f );
34.             // Now apply the offset back to the vertices in model space
35.             v.vertex += mul(_World2Object, vv);
36.         }
37.         // This is just a default surface shader
38.         void surf (Input IN, inout SurfaceOutput o) {
39.             half4 c = tex2D (_MainTex, IN.uv_MainTex);
40.             o.Albedo = c.rgb;
41.             o.Alpha = c.a;
42.         }
43.         ENDCG
44.     }
45.     // FallBack "Diffuse"
46. }

 

That's not really enough information to offer any help. In which way does it not work?