Apple's iPad finally got a clock app with the free iOS 6 update; trouble is, the Swiss design was trademarked. Apple

ZURICH (Reuters) - Apple, sensitive about protecting its own designs, has struck a deal to use Swiss railway operator SBB's trademark station clock design on iPads and iPhones.

SBB, which holds the trademark for a 1944 design by Zurich-born engineer Hans Hilfiker, said last month it might challenge the U.S. company after the clock appeared on a new operating system for the iPad.

"For the use of the clockface on certain Apple devices such as iPads and iPhones, the parties have negotiated an arrangement that enables Apple to use the SBB station clock under a license agreement," SBB said on Friday.

The cost of the licensing fee and further detail of the agreement will remain confidential.

"It is a design icon that has obviously lost none of its appeal in the digital age," the SBB said. "Even now, it symbolises the innovation and reliability that are key qualities attributed to both SBB and Switzerland as a whole."

Hilfiker designed the minimalist clock to help travellers check the time at a distance while hurrying to catch trains.

In 1953, he added a red second hand in the shape of a railway guard's signaling disc, which pauses briefly at the top of each minute "to enable trains to depart punctually," as he put it.

The Design Museum in London and the Museum of Modern Art in New York both included Hilfiker's clock among examples of outstanding 20th-century design.

Apple won a sweeping legal victory in August when a U.S. jury found Samsung Electronics had copied critical features of the iPad and iPhone.