Currently the drag and drop API is only enabled on iPad, not iPhone. This is problematic for applications with drag and drop in their interfaces because they need to reimplement the drag and drop interactions from scratch in JavaScript to support the iPhone. On iPad, everything works as expected, and importantly, feels native to the system. Even if drag and drop is not supported between applications on iOS where it is on iPadOS, native apps on iPhone still support drag and drop within them. For example, it's possible to reorder lists using drag and drop (e.g. Reminders), or move items between locations (e.g. Files). Web applications should also support these interactions without needing to reimplement them completely from scratch. For some precedent of drag and drop support on phones, Chrome on Android does support the drag and drop API. Safari on iPhone is currently the only browser that doesn't support it. I'm hoping that since iPad Safari already supports drag and drop, enabling it on iPhone won't be too difficult. Thank you for considering!
<rdar://problem/75969985>
I’ll second this request. While working on an interface that uses the native DnD API, I noticed that it works pretty great in iPadOS but not iOS, which is what prompted me to come here and search for info. Having that API implemented in iOS WebKit would be a big boost toward advancing its compatibility and capabilities. It’s currently supported on most other platforms, though often with quirks and small differences. Opening up support to the iOS Safari market could push that to a better place for developers to use. Also, many developers (including myself) who want up add this type of functionality are forced to implement their own custom DnD using the Touch Events API or other methods. This increases development time, code size, and project complexity. It would be a boon to have a true cross-browser, native option available without needing to create functionality from scratch.
This appears to be fixed on iOS 15! Drag and drop even works between different apps. Thank you!! https://twitter.com/malonso/status/1439999537133678593