badoo/Chatto

NSLayoutConstraint error when using expandable input and switching input

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#577 opened on May 22, 2019

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bughelp wanted

Description

Reproducible with the demo app, using the "Chat with expandable input" example.

Steps to reproduce:

  1. Press the keyboard chat input icon.
  2. Press the camera chat input icon.

The console will show the following error:

2019-05-22 10:55:34.230615-0400 ChattoApp[3658:2922342] [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. 
(
    "<_UILayoutSupportConstraint:0x2814a9f90 _UILayoutSpacer:0x2808e9e00'UIVC-topLayoutGuide'.height == 64   (active)>",
    "<_UILayoutSupportConstraint:0x2814a9810 V:|-(0)-[_UILayoutSpacer:0x2808e9e00'UIVC-topLayoutGuide']   (active, names: '|':Chatto.BaseChatViewControllerView:0x101c64670 )>",
    "<NSLayoutConstraint:0x2814a94a0 V:[UIView:0x101ca67e0]-(667)-|   (active, names: '|':Chatto.BaseChatViewControllerView:0x101c64670 )>",
    "<NSLayoutConstraint:0x2814df110 UIView:0x101d53d00.height == 44   (active)>",
    "<NSLayoutConstraint:0x2814c06e0 V:|-(0)-[UIView:0x101d53d00]   (active, names: '|':ChattoAdditions.ChatInputBar:0x101c3ea50 )>",
    "<NSLayoutConstraint:0x2814c27b0 V:[UIView:0x101d53d00]-(0)-|   (active, names: '|':ChattoAdditions.ChatInputBar:0x101c3ea50 )>",
    "<NSLayoutConstraint:0x2814c1900 UIView:0x101ca67e0.top == ChattoAdditions.ChatInputBar:0x101c3ea50.top   (active)>",
    "<NSLayoutConstraint:0x2814c20d0 V:[ChattoAdditions.ChatInputBar:0x101c3ea50]-(0)-|   (active, names: '|':UIView:0x101ca67e0 )>",
    "<NSLayoutConstraint:0x2814aa580 V:[_UILayoutSpacer:0x2808e9e00'UIVC-topLayoutGuide']-(>=0)-[UIView:0x101ca67e0]   (active)>",
    "<NSLayoutConstraint:0x2814f4230 'UIView-Encapsulated-Layout-Height' Chatto.BaseChatViewControllerView:0x101c64670.height == 667   (active)>"
)

Will attempt to recover by breaking constraint 
<NSLayoutConstraint:0x2814df110 UIView:0x101d53d00.height == 44   (active)>

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.
2019-05-22 10:55:34.243398-0400 ChattoApp[3658:2922342] [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. 
(
    "<_UILayoutSupportConstraint:0x2814a9f90 _UILayoutSpacer:0x2808e9e00'UIVC-topLayoutGuide'.height == 64   (active)>",
    "<_UILayoutSupportConstraint:0x2814a9810 V:|-(0)-[_UILayoutSpacer:0x2808e9e00'UIVC-topLayoutGuide']   (active, names: '|':Chatto.BaseChatViewControllerView:0x101c64670 )>",
    "<NSLayoutConstraint:0x2814aa580 V:[_UILayoutSpacer:0x2808e9e00'UIVC-topLayoutGuide']-(>=0)-[UIView:0x101ca67e0]   (active)>",
    "<NSLayoutConstraint:0x2814a94a0 V:[UIView:0x101ca67e0]-(667)-|   (active, names: '|':Chatto.BaseChatViewControllerView:0x101c64670 )>",
    "<NSLayoutConstraint:0x2814f4230 'UIView-Encapsulated-Layout-Height' Chatto.BaseChatViewControllerView:0x101c64670.height == 667   (active)>"
)

Will attempt to recover by breaking constraint 
<NSLayoutConstraint:0x2814aa580 V:[_UILayoutSpacer:0x2808e9e00'UIVC-topLayoutGuide']-(>=0)-[UIView:0x101ca67e0]   (active)>

Contributor guide

Tech stack
swiftios
Domain
mobile
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
fresh
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
SwiftiOS developmentAuto Layout basics
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
60
Research direction
Investigate the layout constraints in the expandable input bar. The error occurs when switching between keyboard and camera input. Focus on the ChatInputBar view's height constraint (44 points) and its relationship to the top layout guide. Check the ChatInputBar's constraints in the storyboard or code, especially the height constraint that gets broken. Ensure that all constraints are properly updated when switching input modes.