[iOS] fix bug, when array has subtype, which is redefined naturalType scheme, ...

...code generator gernates error in source codes.

ex :

{
    "name":"numberString",
    "base-type":"string",
    "regex" : "|^ONE$|^TWO$|^THREE$"
},

{
     "name" : "numberStringArray",
     "base-type" : "array",
     "subType" : ["numberString"],
}

in this case generated code had "#error -.....".
and it was bug.