As noted by the blog Ata Distance, Octopus Cards Limited today announced that Apple Pay support has been delayed until later in 2020, after previously indicating that the rollout would be completed by the end of 2019.
Apple Pay support will allow the Octopus card to be added to the Wallet app for contactless fare payment using an iPhone or Apple Watch. Express Transit mode will likely be supported, allowing for tap-and-go payment without needing to authenticate the iPhone or Apple Watch with Face ID, Touch ID, or a passcode.
2019 was a big year for Apple Pay with Express Transit mode, with major cities like London and New York City rolling out support. Other cities like Philadelphia, San Diego, Shenzhen, and Washington, D.C. also have plans to support Apple Pay in 2020. Apple maintains a list of supported cities on its website.