An estimate of what fraction of the current navigation has been loaded.
- iOS 8.0+
- macOS 10.10+
This value ranges from
1.0 based on the total number of bytes expected to be received, including the main document and all of its potential subresources. After navigation loading completes, the
estimatedProgress remains at
1.0 until a new navigation starts, at which point the
estimatedProgress is reset to
WKWebView class is key-value observing (KVO) compliant for this property.