CODEWITHSUNDEEP
objective-cioscocoa-touchuipinchgesturerecognizer
user1337645
user1337645

Reputation: 473

How to detect pinch in gesture vs pinch out gesture?

Instead of scaling, which I think pinch gesture is usually used for, I am looking to just detect whether the pinch was a pinch in vs pinch out so I can collapse or expand some table sections. How would I go about doing that?

Upvotes: 7

Views: 8052

Answers (3)

Mundi
Mundi

Reputation: 80265

Well, that seems an easy one. The UIPinchGestureRecognizer class has only two properties, scale and velocity. It seems logical that a negative scale would mean an inward pinch, a positive scale an outward pinch.

NB: "negative" might be misleading. "Smaller" is 0.0 < scale < 1.0, "bigger" is scale > 1.0.

Upvotes: 8

ScorpionKing2k5
ScorpionKing2k5

Reputation: 2501

The "scale" property is less than 1 for pinch-in gesture and greater than 1 for pinch-out. This happens for all pinches with 2 fingers.

What I also observed was that if I pinched in with 5 fingers (which is the shortcut to minimize-to-home), the scale value comes exactly 1.0 - everytime. But this is not supported by any Apple documentation that I'm aware of.

You can experiment what the values are coming by simply putting an NSLog in your pinch handling selector

NSLog(@"Scale: %.2f | Velocity: %.2f",pinch.scale,pinch.velocity);

Upvotes: 12

Jon Deokule
Jon Deokule

Reputation: 1636

You were right to look at the scale property however it switches around 1, not zero.

    - (BOOL) pinchWasOutwards:(UIGestureRecognizer *)gestureRecognizer
    {
        return gestureRecognizer.scale > 1;
    }

Upvotes: 3

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