Can't get constraints right in iOS8 custom keyboard

Question

I'm having major problems with auto layout in iOS 8. I'm working on a custom keyboard, but I can not get the view to display at the correct height. The rendered view on the device comes out too low, more like the intended height of the UIImageView alone. I've set the constraints as shown in the image:

XCode Screenshot

But I keep getting this error in the log, that tells me nothing (probably because I don't understand where to look):

2014-12-06 19:56:45.095 [40268:12181198] 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:0x600000096940 V:[UIInputView:0x7fe780d3f600(246)]>",
    "<NSLayoutConstraint:0x600000097390 'UIView-Encapsulated-Layout-Height' V:[UIInputView:0x7fe780d3f600(0)]>"
)

Will attempt to recover by breaking constraint 
<NSLayoutConstraint:0x600000096940 V:[UIInputView:0x7fe780d3f600(246)]>

Make a symbolic breakpoint at UIViewAlertForUnsatisfiableConstraints to catch this in the debugger.
The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in <UIKit/UIView.h> may also be helpful.

I've tried following the code in iOS 8 Custom Keyboard: Changing the Height, but it still wont work.

Edit:

I'm setting my height constraint using the following function:

override func updateViewConstraints() {
    super.updateViewConstraints()
    // Add custom view sizing constraints here
    let changeToOrientation = deviceInfoService.getOrientationForView(self.inputView)

    if (changeToOrientation == Orientation.Portrait) {
        self._heightConstraint!.constant = 246
        self.inputView.addConstraint(self._heightConstraint!)
    } else {
        self._heightConstraint!.constant = 192
        self.inputView.addConstraint(self._heightConstraint!)
    }
}

Could you add the rest of the log as well? Specifically the part about `translatesAutoresizingMaskIntoConstraints` that comes before. — Rick, Dec 04 '14 at 22:22
With AutoLayout don't you generally want to set `.translatesAutoresizingMaskIntoConstraints = no`? — mc01, Dec 04 '14 at 23:33

score 6 · Answer 1 · answered Dec 07 '14 at 14:48

6

This looks like a bug in the iOS Custom Keyboard implementation. The workaround currently is to adjust your constraint's priority to more/less than 1000

answered Dec 07 '14 at 14:48

nurnachman

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Setting the priority on "my" constraint to 999 removes the error in the log. Yet the height remains correct - so I guess it's working. – Malakim Dec 08 '14 at 20:03
so choose my answer :) – nurnachman Dec 09 '14 at 17:13

score 2 · Accepted Answer · answered Dec 03 '14 at 20:17

2

The error tells you that you have conflicting constraints. UIView-Encapsulated-Layout-Height seems to be a pre-defined height (When searching I mostly found references to its usage in UICollectionView). My guess is that it's the height defined by the OS that your keyboard is allowed to be. The other constraint is most likely the intrinsic content size of your created view (316 and 30 does indeed add up to 246).

My conclusion is that you probably did something wrong when you changed the height. As I'm not too familiar with keyboard extension development I can't tell you what. However when it comes to the Today Extensions which I have worked a bit with, there was a method you could override which specified the height of the widget.

answered Dec 03 '14 at 20:17

Rick

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The App Extension Programming Guide says: "You can adjust the height of your custom keyboard’s primary view using Auto Layout. By default, a custom keyboard is sized to match the system keyboard, according to screen size and device orientation. A custom keyboard’s width is always set by the system to equal the current screen width. To adjust a custom keyboard’s height, change its primary view's height constraint. In iOS 8.0, you can adjust a custom keyboard’s height any time after its primary view initially draws on screen." Which is what I *think* I'm doing. :) – Malakim Dec 03 '14 at 20:53
But as far as I can see you have no height constraint on the `UIInputView`, only on its subviews. Does it work if you add that? – Rick Dec 04 '14 at 07:53
I set the height constrain for the input view in code - as shown in my edit. I can't set a height constraint on the input view in IB for some reason. – Malakim Dec 04 '14 at 11:14
I see. And you're sure that method gets called as it should? – Rick Dec 04 '14 at 19:48
Seems to be - if I put a breakpoint in it, it will get triggered when the kb is launching. Stepping through the function, it seems to do what it's supposed to. – Malakim Dec 04 '14 at 20:45
Did you try using this approach instead? http://stackoverflow.com/a/25137945/1091402 Putting the code in `viewDidAppear` – Rick Dec 04 '14 at 22:20
Actually - doing it in viewDidAppear makes the view render at the correct height. Still get the constraint violation in the log, though. – Malakim Dec 06 '14 at 19:07
Did you make sure `translatesAutoresizingMaskIntoConstraints` is set to `NO` on all views? – Rick Dec 06 '14 at 22:35

score 1 · Answer 3 · answered Dec 06 '14 at 19:41

1

This looks similar to how a TodayExtension height can be provided. Try this:

self.preferredContentSize = CGSizeMake(320, 246);

That's how I set the height of my today extension vs setting height constraints explicitly. I'll try this myself, just putting together a sample keyboard project now.

answered Dec 06 '14 at 19:41

Henry T Kirk

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What did you find out? – nurnachman Jan 25 '15 at 13:37

Can't get constraints right in iOS8 custom keyboard

3 Answers3