ios - How to detect whether a SwiftUI gesture failed?

In the following example if only the long press will be performed, there is (apparently) no (built-in) way to find out that the drag gesture had failed (if I just lift my finger off the screen for example)

Is there a way to detect wether the second gesture had failed or hasn't been started?

.gesture(
    LongPressGesture()
        .onEnded { _ in
            // First gesture completed ...
        }
        .sequenced(
            before:
                DragGesture()
                    .onEnded { gesture in
                        // Second gesture ended (not called if it has failed) ...
                    }
        )
        .onEnded { _ in
           // Only called if both gestures succeed...
        }
)

Is there a way to detect wether the second gesture had failed or hasn't been started?

.gesture(
    LongPressGesture()
        .onEnded { _ in
            // First gesture completed ...
        }
        .sequenced(
            before:
                DragGesture()
                    .onEnded { gesture in
                        // Second gesture ended (not called if it has failed) ...
                    }
        )
        .onEnded { _ in
           // Only called if both gestures succeed...
        }
)

Share Improve this question edited Jan 30 at 14:34 Benzy Neez 22.5k3 gold badges15 silver badges43 bronze badges asked Jan 30 at 12:53 Petru Lutenco 3594 silver badges14 bronze badges

Perhaps you could consider a position check to see whether the objects was moved your minimum desired distance – not_a_nerd Commented Jan 30 at 13:25

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1 Answer 1

Sorted by: Reset to default 2

You can use exclusively(before:) to achieve this effect. If you have A.exclusively(before: B), then SwiftUI will try to recognise gesture B only if A fails.

In this case, A would be the long press + drag gesture, and B would be just the long press gesture. If B is triggered, that means there is a long press but A failed, which implies that it is the drag gesture that failed.

.gesture(
    LongPressGesture()
        .onEnded { _ in
            print("Long press completed")
        }
        .sequenced(
            before: DragGesture()
                .onEnded { gesture in
                    print("Drag completed")
                }
        )
        .onEnded { x in
            print("Both completed")
        }
        .exclusively(
            before: LongPressGesture()
                .onEnded { _ in print("Drag failed") }
        )
)

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