Did they have the swastika in World War 1?
No, the Swastika was the symbol of the Nazi party. The party was
formed after the great war by disaffected men unhappy at the
perceived injustice of the treaty of Versailles and what they saw
as the weak Weimar republic.
Yes, the Swastika was used in WW1 by various units. The Swastika
was an ancient symbol and the American Indians used it as a good
luck symbol. The US 45th Infantry Division wore a shoulder sleeve
insignia that included a Swastika because of its association with
Oklahoma Indians. (Later it became a Red Diamond with a Yellow
Swastika which was changed to a Yellow Thunderbird at the outbreak
of WW2---because of its association with the Nazi's.)
The Swastika was painted on several WW1 aircraft. One of
France's leading Ace had a large swastika painted on the sides and
top of the fuselage behind the cockpit. The Lafeyette Escadrille,
composed of Americans who volunteered to fly for the French, had
the head of an Indian Chief painted on their aircraft and on the
bonnet was a small swastika.
The Finnish national insignia was a Blue Swastika but I'm not
sure if it was used during WW1 or after. During WW2 the Finnish
national insignia painted on their aircraft was a white circle with
a Blue Swastika. It may have been used in WW1.