Lucio Dalla, an Italian singer-songwriter who sold millions of records worldwide and composed songs for some of Italy’s most famous film directors, died Thursday of an apparent heart attack in Montreux, Switzerland, during a European concert tour. He was 68.Dalla, whose musical genres ranged from folk to jazz to classical, gave a concert Wednesday in the Swiss city known for its music and “was in fine form,” said Pascal Pellegrino, the director of Montreux’s “culture season.” Pellegrino said the performance was warmly applauded, and Dalla stayed on to chat with fans. Dalla’s haunting melody “Caruso” sold 9 million copies worldwide and was sung by the late opera great Luciano Pavarotti with Dalla at a 1992 concert in Modena. Dalla toured abroad frequently, including in the U.S., sometimes with another famed Italian folksong writer, Francesco De Gregori. Promoted by another Italian singer and songwriter, Gino Paoli, Dalla started performing in the 1960s. In 1977, Dalla’s first album with songs written by himself — “How Deep Is the Sea” — came out. He produced new albums nearly every year over the next few years, including the popular “Banana Republic.” Another popular song was his 1990 “Beware of the Wolf” on the album “Cambio,” which sold nearly 1.4 million copies, according to Dalla’s website. His version of Prokofiev’s “Peter and the Wolf” was performed in Rome’s Santa Cecilia auditorium in 1997. He also wrote an opera “Tosca. Amore disperato,” inspired by Puccini’s “Tosca.” Dalla composed songs for some of Italian film directors including Mario Monicelli, Michelangelo Antonioni, Carlo Verdone and Michele Placido. Much of Dalla’s work was inspired by his passion for the sea.