The set of touch properties for which updated values are expected in the future.
- iOS 9.1+
- tvOS 9.1+
This property contains a bitmask of constants indicating which touch properties could not be reported immediately, and for which an update is expected later. When this property contains a non empty set, you can expect UIKit to call the
touches method of your responder or gesture recognizer at a later time with the updated values for the given properties. Attach the value in the
estimation property to your app's copy of the touch data. When UIKit calls the
touches method later, use the estimation update index of the new touch to locate and update your app's copy of the touch data.
When this property contains an empty set, no more updates are expected. In that scenario, the estimated or updated value is the final value.