Open Radar

 
Area:
Foundation

Summary:
NSProgress instance may be built like a tree structure, with parents and child.
If one of the children progress instance is in an indeterminate state, the whole tree, up from the child is in the indeterminate state, therefore I suggest that parent progress should update the indeterminate value (and notify with KVO).

That'd help to update visual progress indicator to reflect the current state of the progress.

Steps to Reproduce:
NSProgress *progress1 = [NSProgress discreteProgressWithTotalUnitCount:1];
NSProgress *progress2 = [NSProgress discreteProgressWithTotalUnitCount:0];

// progress1->progress2
[progress1 addChild:progress2 withPendingUnitCount:1];

Expected Results:
progress1.isIndeterminate is YES

Observed Results:
progress1.isIndeterminate is NO

Version:
iOS 10.3.2

Notes:
Or let traverse the tree to determine the value by ourselves