void setInt32(int byteOffset, int value, [ Endianness endian = Endianness.BIG_ENDIAN ])

Sets the four bytes starting at the specified byteOffset in this object to the two's complement binary representation of the specified value, which must fit in four bytes.

In other words, value must lie between -231 and 231 - 1, inclusive.

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

Source 

void setInt32(int byteOffset, int value,
    [Endianness endian = Endianness.BIG_ENDIAN]);