During WWDC 2021 this morning, Apple has fully upgraded iOS, iPadOS, watchOS, tvOS and macOS. As a tablet enthusiast with iPad as the core, let me talk about the iPadOS 15 released this time. First of all, I think the biggest upgrade point this time is that iPadOS 15 supports mixing of widgets and icons. Apple provides a more convenient multitasking operation for iPadOS 15, users can more conveniently open multitasking, switch applications, manage background multitasking, and close applications. Among iPadOS, memo has always been a very important official application. Finally, in Swift Playgrounds, users can create and publish iPadOS and iOS applications from scratch, and upload them to the App Store. Overall, I think the highlights of iPadOS 15 introduced during this WWDC are limited. Among them, the upgrade of Swift Playgrounds may be good news for some iOS developers. The changes to the desktop are a pain point for me, but it does make users wait too long.