ipFields = uint8(str2double(split('126.96.36.199', '.')))';
Each field of an Ip address is an 8 bit (1 byte) integer, which can be represented by 2 digits in hexadecimal. If you squish the four 8 bit fields together, you get a single 32 bit integer which can be represented by 8 hexadecimal digits.
188.8.131.52 => [192 192 192 2] => [0C 0C 0C 02] => 0C0C0C02 => 3233857538
The typecast is where you "squish" the individual bytes together.
The field reordering is necessary due to the order of bits and bytes in memory. Different systems store bits in different orders. Some systems store data most significant bit, MSB, first while other store data least significant bit first, LSB. Some systems put the most significant byte before the least significant byte, which is called big endian, while others do the revers which is called little endian. You need to be aware of how your system stores data in order to correctly order the bytes before you squish them together.