UIScrollView.isTracking cannot be observed with NSKeyValueObservation
| Originator: | kylebshr | ||
| Number: | rdar://47799272 | Date Originated: | 2/4/2019 |
| Status: | Open | Resolved: | |
| Product: | UIKit | Product Version: | Xcode 10.1 (10B61) |
| Classification: | Other Bug | Reproducible: | Yes |
Summary:
Observing UIScrollView.isTracking using NSKeyValueObservation does not work. The closure is not called when the value changes, unlike other properties such as isHidden. See the attached project for an example.
Steps to Reproduce:
Implement the following in a project with a scroll view:
self.trackingObservation = scrollView.observe(\.isTracking) { [weak self] scrollView, _ in
print(scrollView.isTracking)
}
Expected Results:
When the scroll view isTracking property changes, the observation closure should be called.
Actual Results:
The observation closure is not called when the isTracking property changes.
Version/Build:
Xcode 10.1 (10B61)
iOS Simulator 12.1 (16B91)
iOS 12.1.3 on iPhone 7
Comments
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