UITableViewController: programmatically autolayout bug on iOS 7 - ios

Question

I want to have a UIView programmatically added to a UITableViewController which is using autolayout...
I have the following code inside of the viewDidLoad of a UITableViewController:
UIView *centerView = [[UIView alloc] init];
[centerView setTranslatesAutoresizingMaskIntoConstraints:NO];
centerView.backgroundColor = [UIColor greenColor];
[self.view addSubview:centerView];
// Width constraint, half of parent view width
[self.view addConstraint:[NSLayoutConstraint constraintWithItem:centerView
attribute:NSLayoutAttributeWidth
relatedBy:NSLayoutRelationEqual
toItem:self.view
attribute:NSLayoutAttributeWidth
multiplier:0.5
constant:0]];
// Height constraint, half of parent view height
[self.view addConstraint:[NSLayoutConstraint constraintWithItem:centerView
attribute:NSLayoutAttributeHeight
relatedBy:NSLayoutRelationEqual
toItem:self.view
attribute:NSLayoutAttributeHeight
multiplier:0.5
constant:0]];
// Center horizontally
[self.view addConstraint:[NSLayoutConstraint constraintWithItem:centerView
attribute:NSLayoutAttributeCenterX
relatedBy:NSLayoutRelationEqual
toItem:self.view
attribute:NSLayoutAttributeCenterX
multiplier:1.0
constant:0.0]];
// Center vertically
[self.view addConstraint:[NSLayoutConstraint constraintWithItem:centerView
attribute:NSLayoutAttributeCenterY
relatedBy:NSLayoutRelationEqual
toItem:self.view
attribute:NSLayoutAttributeCenterY
multiplier:1.0
constant:0.0]];
If I now run the app on iOS 8 all working well:
If I run it on iOS 7, the app crashes with the following error:
*** Assertion failure in -[UITableView layoutSublayersOfLayer:], /SourceCache/UIKit_Sim/UIKit-2935.137/UIView.m:8794
If I set setTranslatesAutoresizingMaskIntoConstraints to YES, the app crashes as well with this notice: Unable to simultaneously satisfy constraints

Answer 1

Okay, it looks like UITableView doesn't support Autolayout on iOS 7. So we have to use autoresizing masks. My idea is to put a containerView with autoresizing mask as the tableview's subview and inside that your centerView:
Code:
- (void)viewDidLoad
{
[super viewDidLoad];
[self setupBackgroundView];
}
- (void)setupBackgroundView
{
UIView *backgroundContainerView = [[UIView alloc] initWithFrame:CGRectZero];
backgroundContainerView.backgroundColor = [UIColor cyanColor];
backgroundContainerView.frame = self.tableView.bounds;
backgroundContainerView.autoresizingMask = UIViewAutoresizingFlexibleHeight | UIViewAutoresizingFlexibleWidth;
[self.view addSubview:backgroundContainerView];
UIView *centerView = [[UIView alloc] initWithFrame:CGRectZero];
centerView.translatesAutoresizingMaskIntoConstraints = NO;
centerView.backgroundColor = [UIColor greenColor];
[backgroundContainerView addSubview:centerView];
[backgroundContainerView addConstraint:[NSLayoutConstraint constraintWithItem:centerView
attribute:NSLayoutAttributeWidth
relatedBy:NSLayoutRelationEqual
toItem:backgroundContainerView
attribute:NSLayoutAttributeWidth
multiplier:0.5
constant:0]];
// Height constraint, half of parent view height
[backgroundContainerView addConstraint:[NSLayoutConstraint constraintWithItem:centerView
attribute:NSLayoutAttributeHeight
relatedBy:NSLayoutRelationEqual
toItem:backgroundContainerView
attribute:NSLayoutAttributeHeight
multiplier:0.5
constant:0]];
// Center horizontally
[backgroundContainerView addConstraint:[NSLayoutConstraint constraintWithItem:centerView
attribute:NSLayoutAttributeCenterX
relatedBy:NSLayoutRelationEqual
toItem:backgroundContainerView
attribute:NSLayoutAttributeCenterX
multiplier:1.0
constant:0.0]];
// Center vertically
[backgroundContainerView addConstraint:[NSLayoutConstraint constraintWithItem:centerView
attribute:NSLayoutAttributeCenterY
relatedBy:NSLayoutRelationEqual
toItem:backgroundContainerView
attribute:NSLayoutAttributeCenterY
multiplier:1.0
constant:0.0]];
}
Now centerView moves when the table view gets scrolled. If you want to have it fixed and the content hovering above, you should use backgroundView on UITableView:
- (void)setupBackgroundView
{
UIView *backgroundContainerView = [[UIView alloc] initWithFrame:CGRectZero];
backgroundContainerView.backgroundColor = [UIColor cyanColor];
UIView *centerView = [[UIView alloc] initWithFrame:CGRectZero];
centerView.translatesAutoresizingMaskIntoConstraints = NO;
centerView.backgroundColor = [UIColor greenColor];
[backgroundContainerView addSubview:centerView];
[backgroundContainerView addConstraint:[NSLayoutConstraint constraintWithItem:centerView
attribute:NSLayoutAttributeWidth
relatedBy:NSLayoutRelationEqual
toItem:backgroundContainerView
attribute:NSLayoutAttributeWidth
multiplier:0.5
constant:0]];
// Height constraint, half of parent view height
[backgroundContainerView addConstraint:[NSLayoutConstraint constraintWithItem:centerView
attribute:NSLayoutAttributeHeight
relatedBy:NSLayoutRelationEqual
toItem:backgroundContainerView
attribute:NSLayoutAttributeHeight
multiplier:0.5
constant:0]];
// Center horizontally
[backgroundContainerView addConstraint:[NSLayoutConstraint constraintWithItem:centerView
attribute:NSLayoutAttributeCenterX
relatedBy:NSLayoutRelationEqual
toItem:backgroundContainerView
attribute:NSLayoutAttributeCenterX
multiplier:1.0
constant:0.0]];
// Center vertically
[backgroundContainerView addConstraint:[NSLayoutConstraint constraintWithItem:centerView
attribute:NSLayoutAttributeCenterY
relatedBy:NSLayoutRelationEqual
toItem:backgroundContainerView
attribute:NSLayoutAttributeCenterY
multiplier:1.0
constant:0.0]];
self.tableView.backgroundView = backgroundContainerView;
}

Answer 2

Try removing this line from your code once and build then.
[centerView setTranslatesAutoresizingMaskIntoConstraints:NO];