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AutoLayout with hidden UIViews?

I feel like it's a fairly common paradigm to show/hide UIViews, most often UILabels, depending on business logic. My question is, what is the best way using AutoLayout to respond to hidden views as if their fame was 0x0. Here is an example of a dynamic list of 1-3 features.

Right now i have a 10px top space from the button to the last label, which obviously won't slide up when the the label is hidden. As of right now I created an outlet to this constraint and modifying the constant depending on how many labels I'm displaying. This is obviously a bit hacky since i'm using negative constant values to push the button up over the hidden frames. It's also bad because it's not being constrained to actual layout elements, just sneaky static calculations based on known heights/padding of other elements, and obviously fighting against what AutoLayout was built for.

I could obviously just create new constraints depending on my dynamic labels, but that's a lot of micromanaging and a lot of verbosity for trying to just collapse some whitespace. Are there better approaches? Changing frame size 0,0 and let AutoLayout do it's thing with no manipulation of constraints? Removing views completely?

Honestly though, just modifying the constant from context of the hidden view requires a single line of code with simple calculation. Recreating new constraints with constraintWithItem:attribute:relatedBy:toItem:attribute:multiplier:constant: seems so heavy.

autolayout - make height of view relative to half superview height

have been getting into autolayouts recently and I'm stuck on what seems like a really trivial problem example. I have a view that I want to sit at the top of the screen, and take up half of the screen-height. Simple before autolayout - just tack it in place and tell it to expand vertically when the superview resizes.

Now, I can't for the life of me see how to do it. Here's what I get when I try to set this up:

The bottom space constraint is set to "equals 284", which is absolute and absolutely useless to me when I change to iPhone4 layout, as it keeps 284 points space at the bottom of the screen, and shrinks the view to no longer be half the size of the screen. And there's no way of setting that constraint to equal some fraction of any other view's height..

After struggling for a while, the only way I can think of doing this would be to introduce another view below this view, pin their heights equally, have them sit above and below each other and then set the second (bottom) view to be invisible.. which seems a bit ugly!

Am I missing something obvious?..

Auto layout constraints issue on iOS7 in UITableViewCell

I'm using auto layout constraints programmatically to layout my custom UITableView cells and I'm correctly defining the cell sizes in tableView:heightForRowAtIndexPath:

It's working just fine on iOS6 and it does look fine in iOS7 as well

BUT when I run the app on iOS7, here's the kind of message I see in the console:

Break on objc_exception_throw to catch this in the debugger.
The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in <UIKit/UIView.h> may also be helpful.
2013-10-02 09:56:44.847 Vente-Exclusive[76306:a0b] Unable to simultaneously satisfy constraints.
    Probably at least one of the constraints in the following list is one you don't want. Try this: (1) look at each constraint and try to figure out which you don't expect; (2) find the code that added the unwanted constraint or constraints and fix it. (Note: If you're seeing NSAutoresizingMaskLayoutConstraints that you don't understand, refer to the documentation for the UIView property translatesAutoresizingMaskIntoConstraints) 
(
        "<NSLayoutConstraint:0xac4c5f0 V:|-(15)-[UIImageView:0xac47f50]   (Names: '|':UITableViewCellContentView:0xd93e850 )>",
        "<NSLayoutConstraint:0xac43620 V:[UIImageView:0xac47f50(62)]>",
        "<NSLayoutConstraint:0xac43650 V:[UIImageView:0xac47f50]-(>=0)-[UIView:0xac4d0f0]>",
        "<NSLayoutConstraint:0xac43680 V:[UIView:0xac4d0f0(1)]>",
        "<NSLayoutConstraint:0xac436b0 V:[UIView:0xac4d0f0]-(0)-|   (Names: '|':UITableViewCellContentView:0xd93e850 )>",
        "<NSAutoresizingMaskLayoutConstraint:0xac6b120 h=--& v=--& V:[UITableViewCellContentView:0xd93e850(44)]>"
)

Will attempt to recover by breaking constraint 
<NSLayoutConstraint:0xac43650 V:[UIImageView:0xac47f50]-(>=0)-[UIView:0xac4d0f0]>

And indeed there's one of the constraint in that list I don't want :

"<NSAutoresizingMaskLayoutConstraint:0xac6b120 h=--& v=--& V:[UITableViewCellContentView:0xd93e850(44)]>"

and I cannot set the translatesAutoresizingMaskIntoConstraints property of the contentView to NO => it would mess up the entire cell.

44 is the default cell height but I defined my custom heights in the table view delegate so why does the cell contentView has this constraint? What could cause this?

In iOS6 it's not happening and everything looks just fine on both iOS6 and iOS7.

My code is quite big so I won't post it here but feel free to ask for a pastebin if you need it.

To specify how I'm doing it, on cell intialization:

• I create all my labels, buttons, etc
• I set their translatesAutoresizingMaskIntoConstraints property to NO
• I add them as subviews of the contentView of the cell
• I add the constraints on the contentView

I'm also deeply interested in understanding why this happens only on iOS7.

setNeedsLayout vs. setNeedsUpdateConstraints and layoutIfNeeded vs updateConstraintsIfNeeded

I know that the auto layout chain consists in basically 3 different process.

1. updating constraints
2. layout views (here is where we get calculation of frames)
3. display

What's is not totally clear to me is the inner difference between -setNeedsLayout and -setNeedsUpdateConstraints.
On the documentation apple says:

Call this method on your application’s main thread when you want to adjust the layout of a view’s subviews. This method makes a note of the request and returns immediately. Because this method does not force an immediate update, but instead waits for the next update cycle, you can use it to invalidate the layout of multiple views before any of those views are updated. This behavior allows you to consolidate all of your layout updates to one update cycle, which is usually better for performance.

For the first and,

When a property of your custom view changes in a way that would impact constraints, you can call this method to indicate that the constraints need to be updated at some point in the future. The system will then call updateConstraints as part of its normal layout pass. Updating constraints all at once just before they are needed ensures that you don’t needlessly recalculate constraints when multiple changes are made to your view in between layout passes.

for the second.

When I want to animate a view after modifying a constraint and animate the changes I usually call for instance:

[UIView animateWithDuration:1.0f delay:0.0f usingSpringWithDamping:0.5f initialSpringVelocity:1 options:UIViewAnimationOptionCurveEaseInOut animations:^{
        [self.modifConstrView setNeedsUpdateConstraints];
        [self.modifConstrView layoutIfNeeded];
    } completion:NULL];

I've found out that if I use -setNeedsLayout instead of -setNeedsUpdateConstraints everything work as expected, but if I change -layoutIfNeeded with -updateConstraintsIfNeeded, the animation won't happen.
I've tried to make my own conclusion:

• -updateConstraintsIfNeeded only update constraints but doesn't force the layout to come into the process, thus original frames are still preserved
• -setNeedsLayout calls also -updateContraints method

So when is ok to use one instead of the other? and about the layout methods, do I need to call them on the view that has a change in a constraint or on the parent view?

Layout attributes relative to the layout margin on iOS versions prior to 8.0

What would be causing the following warning (and subsequent alignment issues on iOS 7)?

Attribute Unavailable: Layout attributes relative to the layout margin on iOS versions prior to 8.0

Can I disable autolayout for a specific subview at runtime?

I have a view that needs to have its frame manipulated programmatically - it's a kind of document view that wraps to its content which is then scrolled and zoomed around a superview by manipulating the frame origin. Autolayout fights with this at runtime.

Disabling autolayout completely seems a bit harsh because it could reasonably be used to handle layout for the other views. It seems like what I might want is some kind of "null constraint".

Getting a "This application is modifying the autolayout engine" error?

Been encountering this error a lot in my OS X using swift: "This application is modifying the autolayout engine from a background thread, which can lead to engine corruption and weird crashes. This will cause an exception in a future release."

I have a my NSWindow and I'm swapping in views to the contentView of the window. I get the error when I try and do a NSApp.beginSheet on the window, or when I add a subview to the window. Tried disabling autoresize stuff, and I don't have anything using auto layout. Any thoughts?

Sometimes it's fine and nothing happens, other times it totally breaks my UI and nothing loads

How to resize superview to fit all subviews with autolayout?

My understanding of autolayout is that it takes the size of superview and base on constrains and intrinsic sizes it calculates positions of subviews.

Is there a way to reverse this process? I want to resize superview on the base of constrains and intrinsic sizes. What is the simplest way of achieving this?

I have view designed in Xcode which I use as a header for UITableView. This view includes a label and a button. Size of the label differs depending on data. Depending on constrains the label successfully pushes the button down or if there is a constrain between the button and bottom of superview the label is compressed.

I have found a few similar questions but they don’t have good and easy answers.

"Auto Layout still required after executing -layoutSubviews" with UITableViewCell subclass

Using XCode 4.5 and iOS 6, I'm developing an app with a simple table view with custom cells. I've done this a hundred times in iOS 5 and below, but for some reason the new autoLayout system is giving me a lot of trouble.

I setup my table view and prototype cell in IB, added subviews and wired them up as IBOutlets then setup my delegate and dataSource. However now whenever the first cell is fetched from cellForRowAtIndexPath, I get the following error:

*** Assertion failure in -[ShopCell layoutSublayersOfLayer:], /SourceCache/UIKit_Sim/UIKit-2372/UIView.m:5776

*** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'Auto Layout still required after executing -layoutSubviews. ShopCell's implementation of -layoutSubviews needs to call super.'

I haven't implemented a -layoutSubviews method in my subclassed cell (ShopCell), and even when I try to do that and add the super call as it suggests I still get the same error. If I remove the subviews from the cell in IB, and change it to a standard UITableViewCell, everything works as expected, though of course I'm left with no data in my cells.

I'm almost certain that there's something simple I'm missing, but can't find any documentation or guides to suggest what I've done wrong. Any help would be appreciated.

Edit: Just tried changing it to a UITableViewCell in IB and leaving all the subviews in place, still the same error.

what is NSLayoutConstraint "UIView-Encapsulated-Layout-Height" and how should I go about forcing it to recalculate cleanly

I have a UITableView running under iOS8 I'm using automatic cell heights from constraints in a storyboard.

One of my cells contains a single UITextView and I need it to contract and expand based on user input - tap to shrink/expand the text.

I'm doing this by adding a runtime constraint to the text view and changing the constant on the constraint in response to user events:

-(void)collapse:(BOOL)collapse; {

    _collapsed = collapse;

    if(collapse)
            [_collapsedtextHeightConstraint setConstant: kCollapsedHeight]; // 70.0
        else
            [_collapsedtextHeightConstraint setConstant: [self idealCellHeightToShowFullText]];

    [self setNeedsUpdateConstraints];

}

Whenver I do this, I wrap it in tableView updates and set the tableView's needs updateConstraint:

[tableView beginUpdates];

[_briefCell collapse:!_showFullBriefText];

[tableView setNeedsUpdateConstraints];
// I have also tried 
// [self.tableView reloadRowsAtIndexPaths:@[indexPath] withRowAnimation:UITableViewRowAnimationTop];
// with exactly the same results.

[tableView endUpdates];

When I do this, my cell does expand (and animates whilst doing it) but I get a constraints warning:

2014-07-31 13:29:51.792 OneFlatEarth[5505:730175] Unable to simultaneously satisfy constraints.

Probably at least one of the constraints in the following list is one you don't want. Try this: (1) look at each constraint and try to figure out which you don't expect; (2) find the code that added the unwanted constraint or constraints and fix it. (Note: If you're seeing NSAutoresizingMaskLayoutConstraints that you don't understand, refer to the documentation for the UIView property translatesAutoresizingMaskIntoConstraints) 

(

    "<NSLayoutConstraint:0x7f94dced2b60 V:[UITextView:0x7f94d9b2b200'Brief text: Lorem Ipsum i...'(388)]>",

    "<NSLayoutConstraint:0x7f94dced2260 V:[UITextView:0x7f94d9b2b200'Brief text: Lorem Ipsum i...']-(15)-|   (Names: '|':UITableViewCellContentView:0x7f94de5773a0 )>",

    "<NSLayoutConstraint:0x7f94dced2350 V:|-(6)-[UITextView:0x7f94d9b2b200'Brief text: Lorem Ipsum i...']   (Names: '|':UITableViewCellContentView:0x7f94de5773a0 )>",

    "<NSLayoutConstraint:0x7f94dced6480 'UIView-Encapsulated-Layout-Height' V:[UITableViewCellContentView:0x7f94de5773a0(91)]>"



 )

Will attempt to recover by breaking constraint 

<NSLayoutConstraint:0x7f94dced2b60 V:[UITextView:0x7f94d9b2b200'Brief text: Lorem Ipsum i...'(388)]>

388 is mycalculated height the other constraints on the UITextview are mine from Xcode/IB.

The final one is bothering me - I'm guessing that UIView-Encapsulated-Layout-Height is the calculated height of the cell when it is first rendered - (I set my UITextView height to be >= 70.0) howevcer it doesn't seem right that this derived constraint then overrules an updated user cnstraint.

Worse, although the layout code says it's trying to break my height constraint, it doesn't - it goes on to recalculate the cell height and everything draws as I would like.

So, what is NSLayoutConstraint "UIView-Encapsulated-Layout-Height" (I'm guessing it is the calculated height for automatic cell sizing) and how should I go about forcing it to recalculate cleanly?

How do I adjust the anchor point of a CALayer, when Auto Layout is being used?

Note: Things have moved on since this question was asked; see here for a good recent overview.

Before auto layout, you could change the anchor point of a view's layer without moving the view by storing the frame, setting the anchor point, and restoring the frame.

In an auto layout world, we don't set frames any more, but constraints don't seem up to the task of adjusting the position of a view back to where we want it to. You can hack the constraints to reposition your view, but on rotation or other resizing events, these become invalid again.

The following bright idea doesn't work as it creates an "Invalid pairing of layout attributes (left and width)":

layerView.layer.anchorPoint = CGPointMake(1.0, 0.5);
// Some other size-related constraints here which all work fine...
[self.view addConstraint:
    [NSLayoutConstraint constraintWithItem:layerView
                                 attribute:NSLayoutAttributeLeft
                                 relatedBy:NSLayoutRelationEqual 
                                    toItem:layerView 
                                 attribute:NSLayoutAttributeWidth 
                                multiplier:0.5 
                                  constant:20.0]];

My intention here was to set the left edge of layerView, the view with the adjusted anchor point, to half of its width plus 20 (the distance I want inset from the left edge of the superview).

Is it possible to change the anchor point, without changing the location of a view, in a view that is laid out with auto layout? Do I need to use hardcoded values and edit the constraint on every rotation? I do hope not.

I need to change the anchor point so that when I apply a transform to the view, I get the correct visual effect.

How can I use Autolayout to set constraints on my UIScrollview?

I have spent two days trying out the various solutions for Mixed and Pure Autolayout approaches to achieve what was a trivial scrollview setup prior to autolayout, and it's now official - I must be too stupid. I am setting this up mostly in Storyboard (well, it's just the way it is).

So here's my plea for help.

Viewtree:

UIView
-UIView
-UIView
..-UIScrollview
...-UIButton
...-UIButton
...-UIButton

The buttons are supposed to scroll horizontally (left to right and vice versa). Can someone please let me know how to set the constraints to achieve this using pure Autolayout???

--

I have tried the mixed approach, like so:

UIView
- UIView
- UIView
..-UIScrollview
...-UIView (contentview)
....-UIButton
....-UIButton
....-UIButton

...and setting fixed width and height constraints for the contentview and the translatesAutoresizingMaskIntoConstraints settings as per Apple's TechNote. The buttons and scrollview are set up using constraints. This gets the scrollview scrolling (yay) but alas, it scrolls too far! As far as I can tell, the scroll width is somehow doubled from what I set the contentview at???!!!???

I tried the pure autolayout approach as well, both with contentview and without. All the views are translatesAutoresizingMaskIntoConstraints=NO, except for self.view. The buttons have fixed width/height constraints, and are pinned to all four edges of the scrollview. Nothing scrolls.

So I am totally baffled why I can't get it to work correctly. Any help is much appreciated, and if you need any other info, please ask!

EDIT @Infinity James I have recreated your code exactly in storyboard, but it is not scrolling. (The scrollview contentsize.width is logged as 279, btw). Screenshots:

containerview constraints:

scrollview constraints:

buttonA constraints:

UPDATED Screenshot with solution - buttonZ constraints:

EDIT @ Jamie Forrest So the solution turns out to be the wrong trailing constraint on the last button. Instead of 6441, the value I had set was negative, -6441. The tricky thing is, that when setting the value in storyboard, there are two options in the Pin toolbar:

The Current Canvas Value is negative (leading to no scroll), and the option below is positive (activating scroll). This means I'm not stupid but at least half-blind I guess. Although, to my defense, isn't it somewhat disturbing that XCode doesn't show an error for the "incorrect" setting?

EDITED AGAIN Now this is funny... changing the trailing value from -6441 (no scroll) to 6441 enabled scroll. But my old friend the "too much contentsize" was back, leading to a content size twice as large as what it should be! The solution to get the correct content scroll was to set the trailing constraint to ZERO! This is not obvious when working in Storyboard but looking at @Infinity James' code, it is what it should be.

UITextView that expands to text using auto layout

I have a view that is laid out completely using auto layout programmatically. I have a UITextView in the middle of the view with items above and below it. Everything works fine, but I want to be able to expand UITextView as text is added. This should push everything below it down as it expands.

I know how to do this the "springs and struts" way, but is there an auto layout way of doing this? The only way I can think of is by removing and re-adding the constraint every time it needs to grow.

iOS: Multi-line UILabel in Auto Layout

I'm having trouble trying to achieve some very basic layout behavior with Auto Layout. My view controller looks like this in IB:

The top label is the title label, I don't know how many lines it will be. I need the title label to display all lines of text. I also need the other two labels and the small image to be laid out right below the title, however tall it happens to be. I have set vertical spacing constraints between the labels and small image, as well as a top spacing constraint between the title label and its superview and a bottom spacing constraint between the small image and its superview. The white UIView has no height constraint, so it should stretch vertically to contain its subviews. I have set the number of lines for the title label to 0.

How can I get the title label to resize to fit the number of lines required by the string? My understanding is that I can't use setFrame methods because I'm using Auto Layout. And I have to use Auto Layout because I need those other views to stay below the title label (hence the constraints).

How can I make this happen?

Are NSLayoutConstraints animatable? [duplicate]

I am trying to animate up some views so that they are blocked by the giant keyboard in landscape. It works well if I simply animate the frames, but others have suggested that this is counter-productive and I should be updating the NSLayoutConstraints instead. However, they don't seem to be animatable. Has anyone gotten them to work with success?

//heightFromTop is an NSLayoutConstraint referenced from IB
[UIView animateWithDuration:0.25 animations:^{
    self.heightFromTop.constant= 550.f;
}];

The result is an instant jump to the height in question.