SAN FRANCISCO — Customer relations software company Salesforce says it will join with Apple to create new business apps exclusively for iPhone and iPad. Salesforce said Monday the partnership will focus on three areas: apps for industry and small business to improve customer relations; enabling businesses and developers to create Salesforce apps for iPhone and iPad; and promoting developer career growth by teaching anyone how to build iOS apps. The “Get Started with iOS Development Trail” app is available now, while the others will roll out later this year and in early 2019. The companies say that millions of developers would be able to build their own apps through the new Salesforce Mobile SDK for iOS and through Salesforce’s free web-based learning platform Trailhead. Shares of Salesforce rose 1.5 percent in early week trading.