UITableViewCell frame changes while presenting parent view as modal with UIModalPresentationFormSheet - ios

Question

State of code:
I'm writing my own library for forms in table view (I'm aware of Sensible Cocoa but willing to write my own) and I'm dealing with an issue loosely connected to it.
My form is held by UITableViewController in UITableViewStyleGrouped style. This table view controller is created in a button handler with this code (initialization of form model ommited):
// prepare table view model
_formTableViewController = [[ESCTableViewController alloc] initWithModel:model];
_formTableViewController.navigationItem.rightBarButtonItem = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemCancel
target:self action:#selector(cancelBarButtonItemHandler:)];
_formTableViewController.navigationItem.leftBarButtonItem = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemEdit
target:self action:#selector(editBarButtonItemHandler:)];
// prepare navigation controller containing the tableViewController
ESCNavigationController *navigationController = [[ESCNavigationController alloc] initWithRootViewController:_formTableViewController];
navigationController.modalPresentationStyle = UIModalPresentationFormSheet;
// present navigation view controller
[self presentViewController:navigationController animated:YES completion:nil];
Then, I have UITableViewCell subclassed (as ESCTableViewCell) with style UITableViewCellStyleDefault and each form component is a descendant of ESCTableViewCell using its basic initializer and few properties.
I'm doing my custom rendering like this:
Create my custom field (i.e. UITextField) in initializer of specific cell (ESCTextFieldCell)
prepareForReuse is called by framework on cell reuse, where I remove old observers and invalidate what is needed to invalidate
configWithModel:(Model *)model, where I set properties of the cell, add observers etc.
layoutSubviews is called by framework; meta-code of this process is here:
CGFloat const ESCTextFieldWidthRatio = 0.65f;
CGFloat const ESCFieldHeight = 22.0f;
CGFloat const ESCFieldPadding = 10.0f;
[UIView beginAnimations:nil context:nil];
[UIView setAnimationBeginsFromCurrentState:YES];
// call super layout subviews first
[super layoutSubviews];
// count width of the text field, so it would fit with label
// must round() the results to avoid antialiasing on fractional values
CGFloat contentWidth = self.contentView.frame.size.width;
CGFloat contentHeight = self.contentView.frame.size.height;
CGFloat fieldWidth = round((contentWidth - (2 * ESCFieldPadding)) * ESCTextFieldWidthRatio);
CGFloat fieldOriginY = round((contentHeight / 2) - (ESCFieldHeight / 2));
CGFloat labelWidth = contentWidth - fieldWidth - (4 * ESCFieldPadding);
// set textlabel and textfield frames
self.textLabel.frame = CGRectMake(ESCFieldPadding, 0.0f, labelWidth, contentHeight);
self.textField.frame = CGRectMake(labelWidth + (3 * ESCFieldPadding), fieldOriginY, fieldWidth, ESCFieldHeight);
[UIView commitAnimations];
The Problem:
I'm trying to have the UI as clean as possible, being a perfectionist; thus I want to have table view cells animated on entry/leave of edit mode, which works pretty well in current state of code.
The issue is with presenting the modal view itself with this form table view inside. It seems (proven by simulator - slow animations), that when presenting the modal view, frame of the table view is updated (contracted) by (at least) a few pixels, which is causing both modal view translation animation AND table view cell resize animation, which is at the end causing a not-so-smooth animation of that modal view presentation.
What I would like to understand is, why the table view cell is resizing on modal view presentation as I don't like the idea to hack the code to disable animations when presenting the modal view (it can possibly cause lots of other issues later).
Please, does someone know why this is happening, or do you have some other idea how to override it non-hacky way?
Thank you a lot!
PS: I'm using ARC, but I don't think it matters.
PS2: Problem occures on both iPad1 and iOS Simulator for iOS5.

Answer 1

Miroslav, I'm not sure this helps, but I've been fighting the same thing. And I'm sharing this here because I assume others might wonder what's happening.
It's not just the cell, it's the entire tableview bounds that aren't settled until ViewDidAppear is called.
So let's say you want to bring up a 500x500 modal with a UITableViewController, you launch it with presentViewController, you will have all kinds of resizing going on until it's finally resolved in ViewDidAppear. In my case I've seen it through debugging go from 1024 wide to 320 then finally to 500. And it's that width that I need to determine the resulting height of the table view cells.
It all seems like a hack in this case and I'm not sure there is a clean solution though I wish for one. One way in which I'm testing it now, is that the custom table view cells have a "final width" property that they look at (if it's set) when sizing in layoutSubviews. That way the proper height of the cell can be calculated (based on this fixed width) at anytime prior to the tableview being in it's final form.

Answer 2

I've seen the same issue in some original (read Apple) applications on iOS, so I consider it a feature of the system. It seems, the best we can do, is to hide it as much as possible. Actually, nobody except me noticed the behavior, so I think nobody is bothered.
Consider it not an answer, but a closure. If you have some real solution for the problem, please write it here and I'll mark it as an answer.

Answer 3

Set the UITableView layout to delete outside autosizing.