Apple plans to introduce new versions of the iPhone and iPad in time for the holiday shopping season, seeking to entice shoppers who delayed purchases amid a dearth of new models so far this year. The new iPhone will be unveiled at a Sept. 10 event, according to a person familiar with the plans. Updated iPad models, including an iPad with a thinner body design and an iPad mini with a high-resolution screen will be unveiled later, two people said. Software for the devices, as well as for Mac computers, will also be revamped, Apple said in June. The updates will enable Apple to present a refreshed lineup of its top-selling products to consumers ahead of the year-end holiday shopping season. The iPhone and iPad accounted for almost 70 percent of the company’s sales last quarter. The releases come at a critical time for Apple, whose stock has slumped by a third from a record in September amid slowing profit growth and a scarcity of new products.