How to react to UIControl resize when its data changes - ios

Question

I've built a UIControl subclass to display a 1-month calendar view on
an iPhone. Most months require 5 weeks to display the dates, but
some months need 6, so I've built the control to dynamically resize
itself as needed. I'm using UIView animation to change the frame of
the control here.
The problem is, I now need the other controls on the screen to
move/resize when the calendar changes size. And I really need that
to happen with the animation of the calendar control changing size.
Ideally, I'd do this without coding a bunch of details in my calendar
control about other controls on the screen.
What's the best strategy here? I was hoping I could somehow anchor
the other controls to the frame of the calendar control and have the
platform adjust their location/size as it animates the frame change.
But, thus far, I can't find any combination of struts and springs to
make that happen.
Do I just need to bite the bullet and add my other on-screen controls
to the animation happening inside my calendar control?

Answer 1

I'll be interested to see if there are better answers to this.
At this point, all I know to do is override setFrame on your calendar view and when it changes, send setNeedsLayout to its superview.
But I'm not sure if standard views will autoresize this correctly. Generally geometry flows down the view tree, not up, and you want it to do both.
You may have to implement layoutSubviews on the containing view.

Answer 2

Move the animation logic out of the specific view and into a view controller that manages all of the controls. The view can still figure out its own proper size, and let the view controller ask. For instance:
[self.calendarView setDate:date];
CGSize calendarSize = [self.calendarView sizeForDate:date];
[UIView animateWithDuration:...
animations:^{
... re-layout everything, including the calendarView ...
}];
Another, similar approach:
[self.calendarView setDate:date];
[UIView animateWithDuration:...
animations:^{
[self.calendarView sizeToFit];
... re-layout everything else ...
}];
There are lots of similar approaches based on your preferences. But the key is to move the logic out of the specific view. Usually a view controller is the best solution. If the controls make a logical collection that could go into a single UIView, then you could have that "collection" UIView manage the same thing in its layoutSubviews, but it's more common that a view controller is a better solution here.

Answer 3

Thanks for the help. I tried both of these approaches with success. The override of setFrame and implementation of layoutSubviews worked, but the other controls jumped to their new locations rather than animating to those locations as the calendar control grew.
The approach of moving the other controls during the animation is what I had to go with. However, I wanted to keep the logic of the control pretty self-contained for re-use, so I left the animation in the control but added a delegate to react to size change, and put the delegate call inside the animation block. In full disclosure, I am also animating the new month's calendar onto the control while I'm growing the control, and this way I could do both of those things in the animation block.
So, the end code looks something like this:
// inside the calendar control:
[UIView animateWithDuration:0.5 animations:^{
self.frame = newOverallFrame; // animate the growth of the control
_offScreenCalendar.frame = newOnScreenFrame; // animate new month on screen
_onScreenCalendar.frame = newOffScreenFrame; // animate old month off screen
if (self.delegate)
{
[self.delegate handleCalendarControlSizeChange:newOverallFrame]; // animate other controls per the delegate
}
}];