I’ve been working on a SPA which is built in Node.js and since, my team does not deliver products in native app programming, we use Cordova Apache to build the same product as an iOS app. This approach certainly helps us gain in time, but some deep problems are more difficult to handle. Because, one cannot edit constraints through Cordova platform and hence, some parts of the application remain as black-box for us. Such disadvantage causes trouble when we are not sure about the diagnosis of a defect. Just like the error log below:

Make a symbolic breakpoint at UIViewAlertForUnsatisfiableConstraints to catch this in the debugger.
The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in <UIKitCore/UIView.h> may also be helpful.
2018-10-16 15:24:25.691893+0200 Unibok[70880:8601663] [LayoutConstraints] 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:0x600003509130 'UIButtonBar.maximumAlignmentSize' _UIButtonBarButton:0x7f861b9324d0.height == UILayoutGuide:0x600002f05c00'UIViewLayoutMarginsGuide'.height   (active)>",
"<NSLayoutConstraint:0x600003542850 'UIView-bottomMargin-guide-constraint' V:[UILayoutGuide:0x600002f05c00'UIViewLayoutMarginsGuide']-(9)-|   (active, names: '|':_UIButtonBarStackView:0x7f861b948b10 )>",
"<NSLayoutConstraint:0x600003543070 'UIView-topMargin-guide-constraint' V:|-(10)-[UILayoutGuide:0x600002f05c00'UIViewLayoutMarginsGuide']   (active, names: '|':_UIButtonBarStackView:0x7f861b948b10 )>"
)

Because of the failure above, the keyboard on iPhone or iPad was not usable. Whenever the user touched on a textbox item (<-input->), the application actually triggered the keyboard interface, but the fail above conflicts some constraints and it crashed the keyboard. That was all about the fail.

I spent enough time thinking if this issue was related to some keyboard plugin like many people recommended. (ionic-plugin-keyboard vs. cordova-plugin-keyboard) But the solution was simpler than I thought and our implementation was more innocent than I doubted 🙂

SOLUTION

Recent radar ticket below opened the doors of clarification for me.

https://openradar.appspot.com/radar?id=5018321736957952

As Brent Dearth mentions in the comment, the entire defect was related to a fail in iOS 12.0. And the workaround is to remove your viewport-fit meta tag. The bold text shows the troubled code in my case:

<meta name="viewport" content="maximum-scale=1.0, initial-scale=1.0, user-scalable=no, viewport-fit=cover">

After removing the viewport-fit flag, the app worked on all iOS devices perfectly.

Sercan Leylek / OSLO

P.s. Thanks to Darryl Pogue on solving the issue here.

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