Configure UIScrollView content with autolayout, insets for keyboard, and rotation to landscape

Question

I'm fighting with scrollviews in autolayout (iOS 6,7) for some time now, and it's getting depressing.

Consider a simple entry form

that I want be scrollable, and that should resize in landscape:

Views hierarchy is:

I need to configure proper constraints so that

• scrolling area gets updated properly when keyboard appears and disappears
• content gets resized when device is rotated to landscape and back to portrait
• scrolling area gets updated for landscape and portrait appropriately

Could this be done with no code?

What I get instead

Wrong scroll size when keyboard appears

Content not resized in landscape

Source code to play with:

source code

Answer 1

Behold! After 2 days of searching I believe I may have an answer. Admittedly it cannot be done without code however.

First create your usual top, bottom, leading and trailing constraints from the contentView to the Scroll view. However with the leading and trailing, tick the "Placeholder - Remove at build time" option.

Then inside your viewDidLoad method add the following:

NSLayoutConstraint *leftConstraint =[NSLayoutConstraint
                                     constraintWithItem:self.contentView
                                     attribute:NSLayoutAttributeLeading
                                     relatedBy:0
                                     toItem:self.view
                                     attribute:NSLayoutAttributeLeft
                                     multiplier:1.0
                                     constant:0];
[self.view addConstraint:leftConstraint];

NSLayoutConstraint *rightConstraint =[NSLayoutConstraint
                                     constraintWithItem:self.contentView
                                     attribute:NSLayoutAttributeTrailing
                                     relatedBy:0
                                     toItem:self.view
                                     attribute:NSLayoutAttributeRight
                                     multiplier:1.0
                                     constant:0];
[self.view addConstraint:rightConstraint];

This dynamically adds the leading and trailing constraints from your contentView to the controller's main view (i.e. outside the scroll view).

Then when you rotate your device the input fields are stretched appropriately. This solves your rotation problem, regarding the keyboard appearing there's other answers to this on SO, but basically inside viewDidLoad:

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWasShown:) name:UIKeyboardDidShowNotification object:nil];
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillBeHidden:) name:UIKeyboardDidHideNotification object:nil];

then add these 2 methods:

- (void) keyboardWasShown:(NSNotification *)notification
{
  NSDictionary *info = [notification userInfo];
  CGSize kbSize = [[info objectForKey:UIKeyboardFrameBeginUserInfoKey] CGRectValue].size;
  UIEdgeInsets contentInsets = UIEdgeInsetsMake(0.0, 0.0, kbSize.height, 0);
  self.scrollView.contentInset = contentInsets;
  self.scrollView.scrollIndicatorInsets = contentInsets;
}

- (void) keyboardWillBeHidden:(NSNotification *)notification
{
  UIEdgeInsets contentInsets = UIEdgeInsetsZero;
  self.scrollView.contentInset = contentInsets;
  self.scrollView.scrollIndicatorInsets = contentInsets;
}

Answer 2

Your approach is doable and worth fixing, but if you want an alternative approach, here it is:

Instead of a plain-vanilla UIScrollView, use a UITableView with static rows instead.

In IB, design one custom static table cell that has a UITextField as a subview. After you have that custom static table cell laid out, copy and paste it in the table view until you have 7 identical custom static table cells. Then connect an outlet to each text field.

Create another custom static table cell that has UIButton as a subview. Connect an outlet to the button.

A table view with static cells does not require any table view delegate or data source methods.

The benefit of using a table view instead of plain-vanilla scroll view is that the text field with the first responder status is automatically scrolled above the keyboard when it appears. The other benefit is that you don't have to deal with the scroll view's content view and how its dimensions respond to rotation.

If you use a table view controller for your scene, the default constraints for the table view will handle rotation appropriately. The only constraints you will need to mess with are those that layout the table cell subviews.

However, if you are going to stick with a plain-vanilla scroll view and auto layout, you might want to check out Apple's technical note if you haven't already: https://developer.apple.com/library/ios/technotes/tn2154/_index.html#//apple_ref/doc/uid/DTS40013309