BROOKLYN, N.Y.—Apple Inc. on Tuesday unveiled two more-expensive versions of its Mac personal computers and a redesigned iPad, as it aims to reinvigorate lackluster sales of PCs and tablets with higher-priced devices, the way it did to strengthen its core iPhone business.

The new MacBook Air marks the first full design upgrade of Apple’s most popular laptop model since 2010. It has a high-resolution Retina display, narrower screen borders and Touch ID, while measuring 10% thinner and a quarter-pound lighter than the current...