int getInt32(int byteOffset, [ Endianness endian = Endianness.BIG_ENDIAN ])

Returns the (possibly negative) integer represented by the four bytes at the specified byteOffset in this object, in two's complement binary form.

The return value will be between 231 and 231 - 1, inclusive.

Throws RangeError if byteOffset is negative, or byteOffset + 4 is greater than the length of this object.

Source 

int getInt32(int byteOffset, [Endianness endian = Endianness.BIG_ENDIAN]);