A Boolean value indicating whether the operation is currently executing.
- iOS 2.0+
- macOS 10.5+
- tvOS 9.0+
- watchOS 2.0+
The value of this property is
true if the operation is currently executing its main task or
false if it is not.
When implementing a concurrent operation object, you must override the implementation of this property so that you can return the execution state of your operation. In your custom implementation, you must generate KVO notifications for the
is key path whenever the execution state of your operation object changes. For more information about manually generating KVO notifications, see Key-Value Observing Programming Guide.
You do not need to reimplement this property for nonconcurrent operations.