[ios] How to use auto-layout to move other views when a view is hidden?

I have designed my custom Cell in IB, subclassed it and connected my outlets to my custom class. I have three subviews in cell content which are: UIView (cdView) and two labels (titleLabel and emailLabel). Depending on data available for each row, sometimes I want to have UIView and two labels displayed in my cell and sometimes only two labels. What I am trying to do is to set constraints that way if I set UIView property to hidden or I will remove it from superview the two labels will move to the left. I tried to set UIView leading constraint to Superview (Cell content) for 10px and UILabels leading Constraints for 10 px to the next view (UIView). Later in my code

-(UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(IndexPath *)indexPath {
...
Record *record = [self.records objectAtIndex:indexPath.row];

if ([record.imageURL is equalToString:@""]) {
     cell.cdView.hidden = YES;
}

I am hiding my cell.cdView and I would like the labels to move to the left however they are staying in the same position in Cell. I tried to remove cell.cdView from superview but it didn't work either. I have attached image to clarify what I am about.

I know how to do this programatically and I am not looking for that solution. What I want is to set constraints in IB and I expect that my subviews will move dynamically if other views are removed or hidden. Is it possible to do this in IB with auto-layout?

.....

As no_scene suggested, you can definitely do this by changing the priority of the constraint at runtime. This was much easier for me because I had more than one blocking view which would have to be removed.

Here's a snippet using ReactiveCocoa:

RACSignal* isViewOneHiddenSignal = RACObserve(self.viewModel, isViewOneHidden);
RACSignal* isViewTwoHiddenSignal = RACObserve(self.viewModel, isViewTwoHidden);
RACSignal* isViewThreeHiddenSignal = RACObserve(self.viewModel, isViewThreeHidden);
RAC(self.viewOne, hidden) = isViewOneHiddenSignal;
RAC(self.viewTwo, hidden) = isViewTwoHiddenSignal;
RAC(self.viewThree, hidden) = isViewThreeHiddenSignal;

RAC(self.viewFourBottomConstraint, priority) = [[[[RACSignal
    combineLatest:@[isViewOneHiddenSignal,
                    isViewTwoHiddenSignal,
                    isViewThreeHiddenSignal]]
    and]
    distinctUntilChanged]
    map:^id(NSNumber* allAreHidden) {
        return [allAreHidden boolValue] ? @(780) : @(UILayoutPriorityDefaultHigh);
    }];

RACSignal* updateFramesSignal = [RACObserve(self.viewFourBottomConstraint, priority) distinctUntilChanged];
[updateFramesSignal
    subscribeNext:^(id x) {
        @strongify(self);
        [self.view setNeedsUpdateConstraints];
        [UIView animateWithDuration:0.3 animations:^{
            [self.view layoutIfNeeded];
        }];
    }];

In this case, I map the height of the Author label to an appropriate IBOutlet:

@property (retain, nonatomic) IBOutlet NSLayoutConstraint* authorLabelHeight;

and when I set the height of the constraint to 0.0f, we preserve the "padding", because the Play button's height allows for it.

cell.authorLabelHeight.constant = 0;

In case this helps someone, I built a helper class for using visual format constraints. I'm using it in my current app.

AutolayoutHelper

It might be a bit tailored to my needs, but you might find it useful or you might want to modify it and create your own helper.

I have to thank Tim for his answer above, this answer about UIScrollView and also this tutorial.

In my case I set the constant of the height constraint to 0.0f and also set the hidden property to YES.

To show the view (with the subviews) again I did the opposite: I set the height constant to a non-zero value and set the hidden property to NO.

This is an old question but still I hope it will helps. Coming from Android, in this platform you have an handy method isVisible to hide it from the view but also not have the frame considered when the autolayout draw the view.

using extension and "extend" uiview you could do a similar function in ios (not sure why it is not in UIKit already) here an implementation in swift 3:

    func isVisible(_ isVisible: Bool) {
        self.isHidden = !isVisible
        self.translatesAutoresizingMaskIntoConstraints = isVisible
        if isVisible { //if visible we remove the hight constraint 
            if let constraint = (self.constraints.filter{$0.firstAttribute == .height}.first){
                self.removeConstraint(constraint)
            }
        } else { //if not visible we add a constraint to force the view to have a hight set to 0
            let height = NSLayoutConstraint(item: self, attribute: .height, relatedBy: .equal , toItem: nil, attribute: .notAnAttribute, multiplier: 0, constant: 0)
            self.addConstraint(height)
        }
        self.layoutIfNeeded()
    }

connect constraint between uiview and labels as IBOutlet and set priority member to a less value when set hidden = YES

For the Googlers: building on Max's answer, to solve the padding issue that many have noticed I simply increased the height of the label and used that height as the separator instead of actual padding. This idea could be expanded for any scenario with containing views.

Here's a simple example:

In this case, I map the height of the Author label to an appropriate IBOutlet:

@property (retain, nonatomic) IBOutlet NSLayoutConstraint* authorLabelHeight;

and when I set the height of the constraint to 0.0f, we preserve the "padding", because the Play button's height allows for it.

For those who support iOS 8+ only, there is a new boolean property active. It will help to enable only needed constraints dynamically

P.S. Constraint outlet must be strong, not weak

Example:

@IBOutlet weak var optionalView: UIView!
@IBOutlet var viewIsVisibleConstraint: NSLayoutConstraint!
@IBOutlet var viewIsHiddenConstraint: NSLayoutConstraint!

func showView() {
    optionalView.isHidden = false
    viewIsVisibleConstraint.isActive = true
    viewIsHiddenConstraint.isActive = false
}

func hideView() {
    optionalView.isHidden = true
    viewIsVisibleConstraint.isActive = false
    viewIsHiddenConstraint.isActive = true
}

Also to fix an error in storyboard you'll need to uncheck Installed checkbox for one of these constraints.

UIStackView (iOS 9+)
One more option is to wrap your views in UIStackView. Once view is hidden UIStackView will update layout automatically

The easiest solution is to use UIStackView (horizontal). Add to stack view: first view and second view with labels. Then set isHidden property of first view to false. All constrains will be calculated and updates automatically.

Instead of hiding view, create the width constrain and change it to 0 in code when you want to hide the UIView.

It may be the simplest way to do so. Also, it will preserve the view and you don't need to recreate it if you want to show it again (ideal to use inside table cells). To change the constant value you need to create a constant reference outlet (the same way as you do outlets for the view).

Use two UIStackView Horizontal and Vertical, when some subview view in stack is hidden other stack subviews will be moved, use Distribution -> Fill Proporionally for Vertical stack with two UILabels and need set width and height constaints for first UIView

My project uses a custom @IBDesignable subclass of UILabel (to ensure consistency in colour, font, insets etc.) and I have implemented something like the following:

override func intrinsicContentSize() -> CGSize {
    if hidden {
        return CGSizeZero
    } else {
        return super.intrinsicContentSize()
    }
}

This allows the label subclass to take part in Auto Layout, but take no space when hidden.

the proper way to do it is to disable constraints with isActive = false. note however that deactivating a constraint removes and releases it, so you have to have strong outlets for them.

I think this is the most simple answer. Please verify that it works:

        StackFullView.layer.isHidden = true
        Task_TopSpaceSections.constant = 0.   //your constraint of top view

check here https://www.youtube.com/watch?v=EBulMWMoFuw

Here's how I would re-align my uiviews to get your solution:

1. Drag drop one UIImageView and place it to the left.
2. Drag drop one UIView and place it to the right of UIImageView.
3. Drag drop two UILabels inside that UIView whose leading and trailing constraints are zero.
4. Set the leading constraint of UIView containing 2 labels to superview instead of UIImagView.
5. IF UIImageView is hidden, set the leading constraint constant to 10 px to superview. ELSE, set the leading constraint constant to 10 px + UIImageView.width + 10 px.

I created a thumb rule of my own. Whenever you have to hide / show any uiview whose constraints might be affected, add all the affected / dependent subviews inside a uiview and update its leading / trailing / top / bottom constraint constant programmatically.

This my another solution using priority constraint. The idea is set the width to 0.

1. create container view (orange) and set width.

2. create content view (red) and set trailing space 10pt to superview (orange). Notice trailing space constraints, there are 2 trailing constraint with different priority. Low(=10) and High(<=10). This is important to avoid ambiguity.

3. Set orange view's width to 0 to hide the view.

UIStackView repositions its views automatically when the hidden property is changed on any of its subviews (iOS 9+).

UIView.animateWithDuration(1.0) { () -> Void in
   self.mySubview.hidden = !self.mySubview.hidden
}

Jump to 11:48 in this WWDC video for a demo:

Mysteries of Auto Layout, Part 1

Just use UIStackView and everything will be work fine. No need to worry about other constraint, UIStackView will handle the space automatically.

Try this,I have implemented below code ,

I have one View on ViewController in that added other three views, When any view is hidden other two view will move,Follow below steps. ,

1.ViewController.h File

#import <UIKit/UIKit.h>
@interface ViewController : UIViewController
@property (strong, nonatomic) IBOutlet UIView *viewOne;
@property (strong, nonatomic) IBOutlet UIView *viewTwo;
@property (strong, nonatomic) IBOutlet UIView *viewThree;
@property (strong, nonatomic) IBOutlet NSLayoutConstraint *viewOneWidth;
@property (strong, nonatomic) IBOutlet NSLayoutConstraint *viewTwoWidth;
@property (strong, nonatomic) IBOutlet NSLayoutConstraint *viewThreeWidth;
@property (strong, nonatomic) IBOutlet NSLayoutConstraint *viewBottomWidth;
@end

2.ViewController.m

 #import "ViewController.h"
 @interface ViewController ()
{
  CGFloat viewOneWidthConstant;
  CGFloat viewTwoWidthConstant;
  CGFloat viewThreeWidthConstant;
  CGFloat viewBottomWidthConstant;
}
@end

@implementation ViewController
@synthesize viewOne, viewTwo, viewThree;

- (void)viewDidLoad {
  [super viewDidLoad];
 // Do any additional setup after loading the view, typically from a 
  nib.

  /*
   0  0   0
   0  0   1
   0  1   0
   0  1   1
   1  0   0
   1  0   1
   1  1   0
   1  1   1
   */

  //    [viewOne setHidden:NO];
  //    [viewTwo setHidden:NO];
  //    [viewThree setHidden:NO];

  //    [viewOne setHidden:NO];
  //    [viewTwo setHidden:NO];
  //    [viewThree setHidden:YES];

  //    [viewOne setHidden:NO];
  //    [viewTwo setHidden:YES];
  //    [viewThree setHidden:NO];

  //    [viewOne setHidden:NO];
  //    [viewTwo setHidden:YES];
  //    [viewThree setHidden:YES];


  //    [viewOne setHidden:YES];
  //    [viewTwo setHidden:NO];
  //    [viewThree setHidden:NO];

  //    [viewOne setHidden:YES];
  //    [viewTwo setHidden:NO];
  //    [viewThree setHidden:YES];

 //    [viewOne setHidden:YES];
 //    [viewTwo setHidden:YES];
 //    [viewThree setHidden:NO];

//    [viewOne setHidden:YES];
//    [viewTwo setHidden:YES];
//    [viewThree setHidden:YES];

 [self hideShowBottomBar];
  }

- (void)hideShowBottomBar
{
  BOOL isOne = !viewOne.isHidden;
  BOOL isTwo = !viewTwo.isHidden;
  BOOL isThree = !viewThree.isHidden;

  viewOneWidthConstant = _viewOneWidth.constant;
  viewTwoWidthConstant = _viewTwoWidth.constant;
  viewThreeWidthConstant = _viewThreeWidth.constant;
  viewBottomWidthConstant = _viewBottomWidth.constant;

   if (isOne && isTwo && isThree) {
    // 0    0   0
    _viewOneWidth.constant = viewBottomWidthConstant / 3;
    _viewTwoWidth.constant = viewBottomWidthConstant / 3;
    _viewThreeWidth.constant = viewBottomWidthConstant / 3;
    }
    else if (isOne && isTwo && !isThree) {
     // 0    0   1
    _viewOneWidth.constant = viewBottomWidthConstant / 2;
    _viewTwoWidth.constant = viewBottomWidthConstant / 2;
    _viewThreeWidth.constant = 0;
    }
   else if (isOne && !isTwo && isThree) {
    // 0    1   0
    _viewOneWidth.constant = viewBottomWidthConstant / 2;
    _viewTwoWidth.constant = 0;
    _viewThreeWidth.constant = viewBottomWidthConstant / 2;
    }
    else if (isOne && !isTwo && !isThree) {
    // 0    1   1
    _viewOneWidth.constant = viewBottomWidthConstant;
    _viewTwoWidth.constant = 0;
    _viewThreeWidth.constant = 0;
   }
   else if (!isOne && isTwo && isThree) {
    // 1    0   0
    _viewOneWidth.constant = 0;
    _viewTwoWidth.constant = viewBottomWidthConstant / 2;
    _viewThreeWidth.constant = viewBottomWidthConstant / 2;
   }
   else if (!isOne && isTwo && !isThree) {
    // 1    0   1
    _viewOneWidth.constant = 0;
    _viewTwoWidth.constant = viewBottomWidthConstant;
    _viewThreeWidth.constant = 0;
   }
   else if (!isOne && !isTwo && isThree) {
    // 1    1   0
    _viewOneWidth.constant = 0;
    _viewTwoWidth.constant = 0;
    _viewThreeWidth.constant = viewBottomWidthConstant;
   }
   else if (isOne && isTwo && isThree) {
    // 1    1   1
    _viewOneWidth.constant = 0;
    _viewTwoWidth.constant = 0;
    _viewThreeWidth.constant = 0;
   }
  }

 - (void)didReceiveMemoryWarning {
  [super didReceiveMemoryWarning];
 // Dispose of any resources that can be recreated.
 }
 @end

Hope So this logic will help some one.

What I ended up doing was creating 2 xibs. One with the left view and one without it. I registered both in the controller and then decided which to use during cellForRowAtIndexPath.

They use the same UITableViewCell class. The downside is that there is some duplication of the content between the xibs, but these cells are pretty basic. The upside is that I don't have a bunch of code to manually manage removing view, updating constraints, etc.

In general, this is probably a better solution since they are technically different layouts and therefore should have different xibs.

[self.table registerNib:[UINib nibWithNibName:@"TrackCell" bundle:nil] forCellReuseIdentifier:@"TrackCell"];
[self.table registerNib:[UINib nibWithNibName:@"TrackCellNoImage" bundle:nil] forCellReuseIdentifier:@"TrackCellNoImage"];

TrackCell *cell = [tableView dequeueReusableCellWithIdentifier:(appDelegate.showImages ? @"TrackCell" : @"TrackCellNoImage") forIndexPath:indexPath];

I will use horizontal stackview. It can remove the frame when the subview is hidden.

In image below, the red view is the actual container for your content and has 10pt trailing space to orange superview (ShowHideView), then just connect ShowHideView to IBOutlet and show/hide/remove it programatically.

1. This is when the view is visible/installed.

2. This is when the view is hidden/not-installed.

Adding or removing constraints during runtime is a heavyweight operation that can affect performance. However, there is a simpler alternative.

For the view you wish to hide, set up a width constraint. Constrain the other views with a leading horizontal gap to that view.

To hide, update the .constant of the width constraint to 0.f. The other views will automatically move left to assume position.

See my other answer here for more details:

How to change label constraints during runtime?