Do you mean that you can buy an iPhone with a credit card in Hong Kong?

If so, then it is possible. You can use credit cards with the "UnionPay" logo to pay at Apple stores in Hong Kong. The Hong Kong dollars in the transaction will be automatically converted into RMB according to the UnionPay exchange rate and will be credited to the account. When the time comes, you only need to pay back RMB, which is very convenient.