Introduction
Have you ever encountered a problem where Xcode crashes when you add a scroll view and constrain its subviews? This article will guide you through the process of fixing this issue automatically by taking advantage of Xcode's built-in features and custom scripts.
Context
The bug occurs when you add a scroll view to a view controller and then try to constrain the objects inside the scroll view. Xcode may crash with an "Internal Error Interacted" message. This issue seems to occur when the subviews of the scroll view are not properly positioned or constrained, causing a conflict with Xcode's Auto Layout engine.
Why does this happen?
The exact reason for this bug is not known, but it may be related to how Xcode handles constraints involving a scroll view. When adding subviews to a scroll view, you need to set the content size and constraints carefully to ensure that the scroll view behaves correctly. Improper constraints can cause conflicts and lead to a crash.
Affected versions of Xcode
This issue has been reported in various versions of Xcode, including Xcode 11 and Xcode 12. However, the bug may have been fixed in more recent versions.
Fixing the issue automatically
To fix the issue automatically, you can use a combination of Xcode's built-in features and custom scripts. The following steps outline a solution for fixing the bug using this method:
Step 1: Add the scroll view to the view controller
Begin by adding the scroll view to the view controller as you normally would. Make sure to set its constraints to hug the margins of the view controller's safe area.
Step 2: Add a content view to the scroll view
Now, add a UIView (hereafter referred to as the "content view") to the scroll view. Set its constraints to match the scroll view's bounds. This will create a content area that scrolls within the scroll view itself.
Step 3: Create a custom script to add and constrain subviews
To avoid the risk of improperly setting up constraints, you can create a custom script to add and constrain subviews automatically. Create a new Swift file (e.g., "AutoLayoutScript.swift") and include the following code:
Step 4: Adding and constraining subviews using the script
Now, instead of manually adding subviews and setting up constraints, call the "createAndPositionView" function. This function accepts a view to be added, a container view (the content view), and an array of NSLayoutConstraint. Create instances of UIView and NSLayoutConstraint for the subviews, then pass these to the function to create and constrain them automatically:
By using a custom script to add and constrain subviews within a scroll view, you can mitigate the risk of encountering the "Internal Error Interacted" bug in Xcode. However, it is recommended that you use the latest stable version of Xcode, as it may have already fixed this issue. If you do experience this bug, using the provided solution should help resolve the error automatically.
References
-
Apple Developer Forums: “Scroll View causing crash on addSubview” https://developer.apple.com/forums/thread/122552
-
Stack Overflow: “Xcode 10 Beta 3: ViewDidLoad: Thread 1: signal SIGABRT when adding subview to ScrollView” https://stackoverflow.com/questions/51944500/xcode-10-beta-3-viewdidload-thread-1-signal-sigabrt-when-adding-subview-to-scr