Cannot get a correct buttonMask value from a UIGestureRecognizer instance

Number:rdar://FB8470648 Date Originated:
Status:Open Resolved:
Product:iOS/UIKit Product Version:
Classification: Reproducible:YES
According to we can see that buttonMask is a new property added since ios 13.4.

However, during my development process, I found that I cannot get the correct value from a UIGestureRecognizer instance. It always equals to 0. Actually it should equals to 1 if current button is primary, 2 if secondary.

It is worth mentioning that we can get the correct value from its derived class like the following way,
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
   NSLog(@ā€œ%s event.buttonMask:%dā€, __func__, event.buttonMask);
Even so, we cannot access it from the base class instance, and 'buttonMask' is readonly, we cannot change its value.

If you think it is indeed a mistake, can you solve this problem? This will greatly help our development. Thank you very much!


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