NSSplitView: Controlling divider position during window resize

Question

I have an NSSplitView that's having two panes - a sidebar table view on the left and a web view on the right one. I also have a delegate set that's handling constraints for the sidebar like this:

- (CGFloat)splitView:(NSSplitView *)splitView constrainMaxCoordinate:(CGFloat)proposedMax ofSubviewAt:(NSInteger)dividerIndex {
    return 500.0f;
}

- (CGFloat)splitView:(NSSplitView *)splitView constrainMinCoordinate:(CGFloat)proposedMinimumPosition ofSubviewAt:(NSInteger)dividerIndex {
    return 175.0f;
}

- (BOOL)splitView:(NSSplitView *)splitView canCollapseSubview:(NSView *)subview {
    return NO;
}

It means that the sidebar can only be resized between 175 and 500 pixels and this works fine when using the divider handle. But when resizing the whole window the divider gets repositioned out of these constraints.

Does anybody know how to control this?

Additionally: If I want to store the user's choice of sidebar width, is it a good thought to read it out, save it to a preferences file and restore it later, or is there a more straight-forward way to do this? I noticed that the window's state gets saved in some cases - is this generally happening or do I have to control it?

Thanks in advance

Arne

Answer 1

I initially implemented the NSSplitView delegate functions and ended up with a lot of code to try to do something so simple as limit the minimum size for each of the split view sides.

I then changed my approach and found a clean and extremely simply solution. I simply set a auto layout constant for a width (>= to my desired minimum size) on the NSView for one side of the NSSplitView. I did the same on my other side. With these two simple constraints the NSSplitView worked perfectly without the need for delegate calls.

Answer 2

What you are looking for is:

- (void)splitView:(NSSplitView*)sender resizeSubviewsWithOldSize:(NSSize)oldSize

[sender frame] will be the new size of your NSSplitView after the resize. Then just readjust your subviews accordingly.