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Summary:
Dear AppKitterinos,

I have a view in a storyboard. The view’s wantsLayer is true in the View Effects inspector.

When the view controller’s viewDidLoad runs, the view’s layer is usually (but not always) still nil even though the view’s wantsLayer is always true at this point.

The behavior arises because the view sets its layer in its _finishMakingConnections method, and the view controller sends itself viewDidLoad from its own _finishMakingConnections method. Since the _finishMakingConnections messages are sent using -[NSSet makeObjectsPerformSelector:], the order in which the messages are sent is non-deterministic and (probably due to address space layout randomization) indeed varies across executions.

I’ve attached a project that demonstrates the problem. You may need to run the project many times to reproduce the problem. If you’re having trouble reproducing, try changing the objects in the storyboard, adding instance variables to MyView and/or ViewController, or changing the order in which the classes are defined in ViewController.swift.

When the problem occurs, the output of the test project looks like this:

-------- in viewDidLoad() 
view.wantsLayer=true
view.layer=nil ‼️

-------- in viewDidLoad() (after view.wantsLayer = true)
view.wantsLayer=true
view.layer=0x000060800004e7c0
bootstrap_check_in():  (os/kern) unknown error code (44c)

Love,
Rob


Steps to Reproduce:
 

Expected Results:
 

Actual Results:
 

Version:
Version 9.0 beta (9M136h) / 10.13 Beta (17A264c)

Notes: