How to resize other subviews and parent view when one subview size changes

Question

I have a view which is similar to mail app. I have a scroll view and in that many other subviews. When the user clicks on any textview, it expands to show the text in it. e.g. "to" field in mail. I would want to resize the other subviews such that it starts below the expanded region. How can I do that.

I created the view through IB and I marked it for flexible top margin to facilitate this. But nothing happens automatically and hence I was wondering if I need to call sizethatFits/setneedsLayout.

Answer 1

When the subview resizes, call [[self superview] setNeedsLayout]. In your superview, implement -layoutSubviews to do the actual layout. You'll have to calculate everything yourself. Fixed/flexible margins are relevant to resizing the superview, not on peer views. The default -layoutSubviews does nothing at all; it just gets called at appropriate times.

If you need to force layout to happen at a particular point, then you can call -layoutIfNeeded on yourself or your superview. Read the docs on how this method works. Generally speaking you don't need to call this, though. It will usually get called at the appropriate time if you just use -setNeedsLayout.

Answer 2

This is not an answer but comment to Rob's answer: Thanks for the information. It sure brought in more clarity.