Checking if code is running in Interface Builder

Question

I have custom IBDesignable classes in swift that do some things that cause crashes in Interface Builder. Is there a flag I can check to see if I'm running in interface builder or not? Ideally it would be a precompiler directive (#ifdef COMPILED_FOR_INTERFACE_BUILDER or something like that). I thought maybe I could set a flag myself in prepareForInterfaceBuilder() but that seems messy and doesn't seem to work reliably as it looks class properties are set before that function is called and this can trigger code that causes problems. Seems like there must be a better way. Thanks!

Don't know why this question was voted down. I think it's a great question. (Of course I have no useful answer...) — matt, Jun 10 '15 at 00:35

score 24 · Accepted Answer · answered Jun 10 '15 at 01:43

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From https://developer.apple.com/library/ios/recipes/xcode_help-IB_objects_media/Chapters/CreatingaLiveViewofaCustomObject.html:

You can use the preprocessor macro TARGET_INTERFACE_BUILDER to specify code for inclusion with or exclusion from your custom view class."

answered Jun 10 '15 at 01:43

Ewan Mellor

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Thanks! This was exactly what I was looking for and for some reason no amount of googling turned up that macro. Very useful! – Michael John Ilardi Jun 10 '15 at 07:34
10/10 this is exactly what I needed! – 72A12F4E Dec 06 '18 at 22:53
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Wow, this is going to change my whole life dealing with IB crashes! Thank you x 1000! – disconnectionist Mar 07 '19 at 10:23
Thank you @EwanMellor, this made my day!! – zaitsman Mar 26 '19 at 13:21

Checking if code is running in Interface Builder

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