Shader fails on iOS

I've started to learn to write shaders in Cg, and I've written a few relatively straight-forward shaders, such as Lambertian, Toon and Rim-Lit. When I try to run on my iPhone6, the Lambertian and Toon shaders work just fine, but the Rim-Lit fails, with a warning in xcode saying

Warning: Creation of shader 'Awesome/EdgeLitNormal' failed.WARNING: Shader Unsupported: 'Awesome/EdgeLitNormal' - Pass '' shader state not supported WARNING: Shader Unsupported: 'Awesome/EdgeLitNormal' - Setting to default shader.

All the shaders work just fine in the editor. The code for my shader is

 Shader "Awesome/EdgeLitNormal" {
     Properties {
         _Color ("Color", Color) = (0.3, 1.0, 0.2, 1.0)
         _EdgeColor ("Edge color", Color) = (1.0, 1.0, 1.0, 1.0)
         _EdgePower ("Edge power", Range (0.0, 10.0)) = 1.0
     }
 
     SubShader {
         Pass {
             Tags {
                 "LightMode" = "ForwardBase"
             }
             
             CGPROGRAM
             
             #pragma vertex vert
             #pragma fragment frag
 
             uniform float4 _Color;
             uniform float4 _EdgeColor;
             uniform float _EdgePower;
             
             uniform float4 _LightColor0;
 
             // input-output structs between shader stages
             struct vertexInput {
                 float4 vertex : POSITION;
                 float3 normal : NORMAL;
             };
 
             struct vertexOutput {
                 float4 pos : SV_POSITION;    // SV_ is for DX11
                 float3 normalDir;
                 float3 viewDir;
             };
 
             // vertex shader
             vertexOutput vert(vertexInput v) {
                 vertexOutput o;
                 
                 o.pos = mul(UNITY_MATRIX_MVP, v.vertex);
                 o.normalDir = normalize(mul(float4(v.normal, 0.0), _World2Object)).xyz;
                 o.viewDir = normalize(_WorldSpaceCameraPos.xyz - mul(_Object2World, v.vertex));
                 
                 return o;
             }
 
             // fragment shader
             float4 frag(vertexOutput i) : COLOR {
                 //Lambertian
                 float3 lightDir = normalize(_WorldSpaceLightPos0).xyz;
                 float3 diffuseAmount = max(0.0, dot(i.normalDir, lightDir));
                 float3 finalDiffuse = _LightColor0.xyz * diffuseAmount + UNITY_LIGHTMODEL_AMBIENT;
                 
                 //Edge lighting
                 half edgeAmount = 1 - saturate(dot(i.viewDir, i.normalDir));
                 float3 finalEdge = pow(edgeAmount, _EdgePower) * _EdgeColor;
             
                 return float4(finalDiffuse * _Color + finalEdge, 1.0);
             }
             ENDCG
         }
     }
 
     //Fallback "Diffuse"
 
 }
 

I've tried to look around for info about what's going on, but with so little information in the error-message, it's kind of hard to even know where to start. Does anyone know why this shader wouldn't run on iOS?