I'd like to monitor the fitting width of an UIDatePicker set to the mode of .date on iOS. By fitting width, I mean that usually obtained by systemLayoutSizeFittingSize(CGSize(0, 0)) -- but I need to monitor its change and get the value of it after the change.
I know that it is possible to use UIControlEventValueChanged to monitor the change of the value which implies that its width would change... but I need to know its "preferred" width after the value of the Date Picker gets changed.
I am interested in knowing this because I am laying out the UIKit widgets using a custom algorithm, and it must know the width of the date picker. The date picker displays as a shaded rounded rectangle, so this is needed -- I don't think you can just "force" the date picker to another width.
EDIT: UIDatePicker seems to collapse into mm/dd/yyyy format when the width is set small. If that affects the fitting size, I'd like to monitor for the change of the intrinsic size.
A solution using a changed handler to force update of this value would be also welcome.
In the on-change handler of whatever you're hooking up the DatePicker with, do this:
[datePicker setNeedsLayout];
[datePicker layoutIfNeeded];
CGFloat width = [datePicker systemLayoutSizeFittingSize:UILayoutFittingCompressedSize].width;
The first two lines are needed in order for it to be the latest size and not from before the change.