Apple Inc yesterday announced a rare retail promotion in China, offering four days of discounts on its top-tier iPhones and related accessories in advance of the launch of its next-generation devices. The company, usually reluctant to alter pricing, is to take up to 600 yuan (US$88.83) off the price of its top-line iPhone 13 Pro series from Friday to Monday next week, according to a notice on its Web site. To be eligible, buyers must use one of a select number of payment platforms, such as Ant Group Co’s (????) Alipay (???). Certain AirPods and Apple Watch models are also…