Yesterday, Twitter CEO  Dick Costolo said in an interview that the company views Apple as a “corporate mentor” because of the two companies’ common focus on simplicity. He also mentioned that iOS  signups for  the service have increased three times since the release of iOS 5 (which was on October 12th) .

While being on-stage at the Web 2.0 conference in San Francisco this Monday, he indicated that he expects the results from the partnership with Apple  to be “even better” than originally thought, reports GigaOm. According to the CEO,  daily signups for Twitter from Apple’s iPhone and iPad devices jumped up more than three times on the first day that iOS 5 became available.

Earlier this year, Apple introduced a system-wide level of Twitter into iOS. The benefits from this partnership  with Apple are much greater than just increased users. Costolo also said that  Apple is a like-minded company because of the restraint it exercises on its products, suggesting that  he views the Apple as a mentor.

Those guys [at Apple] are an amazing partner for us. When they think about products and enhancing products they think about editing them,he was reported as saying. [At Twitter] we’re going to offer simplicity in a world of complexity… they’re a corporate mentor to us.

Costolo also confirmed Monday that Twitter is worth $8 billion.