How can I detect a failed drag gesture in a SwiftUI sequenced gesture?

You can detect a “partial” sequence by looking at the enumerated state that a sequenced gesture produces. When you chain gestures using .sequenced(before:), SwiftUI wraps the results in an enum that lets you distinguish between the first phase and the whole (successful) gesture sequence. In your .onEnded handler you can pattern‑match against that value to check whether the second gesture was attempted at all or even if it failed.

For example, you might write:

SWIFTCopied
LongPressGesture()
    .sequenced(before: DragGesture())
    .onEnded { value in
        switch value {
        case .first(let firstValue):
            // Only the long press was recognized and the second gesture never started.
            print("Long press completed; no drag gesture detected.")
            
        case .second(let firstValue, let secondValue?):
            // Both gestures were recognized and the drag gesture has a valid value.
            print("Drag gesture succeeded with value: \(secondValue)")
            
        case .second(_, nil):
            // The long press was recognized, but the drag gesture failed or was cancelled.
            print("Long press completed but the drag gesture failed.")
            
        default:
            break
        }
    }

In the above code, the gesture value is an enum with two cases:

• .first(): Indicates that only the first (long press) part completed.
• .second(,_): Contains the first gesture result plus an optional value for the drag. If the drag wasn’t initiated or failed, that optional will be nil.

Using this pattern matching you can detect when the second gesture wasn’t started (or failed) and respond accordingly.