Cant connect my iPad with Arduino

Hi,
at first. I am Sorry about my English:) But I try my best!

I want to connect my iPad2 with an Arduino Board Mega.
I use a book iOS Sensor Apps with Arduino, but when I write The example Code, like this:

void loop()
while (Serial.available() <= 0) {
Serial.printIn("Hello World");
delay(300);
}
Than Arduino make an error, that somethink is wrong with "printIn"!

Whats wrong here?

(deleted)

Oh:)
Thx! I hope it works than:)

If it helps you remember, the "ln" in "println" means "line". So "println" means "print a line"

ah okay thank you!

Can you use 1 Ethernet shield and any software from the AppStore:

https://itunes.apple.com/us/app/kino-app-inventor/id580553759?l=es&ls=1&mt=8

https://itunes.apple.com/es/app/arduip/id579281736?mt=8