I should say I am using a heavily modified SynchronizedResolver that uses a serial DispatchQueue as a lock and only requires a Resolver.

I agree👍 As we talked in #139, I also want to enhance concurrency model. I'll try to implement concurrency for Assembly/Assembler. If you can show me your modified code, it's very helpful!

How is this coming along? I'm also worried about thread safety.

Right now I'm creating my Assembler with the SwinjectStoryboard's defaultContainer. I'm thinking of exposing the defaultContainer's threadsafe view (synchronize) instead of the Assembler's resolver. Thoughts?

So what is the mechanism for exposing a thread safe resolver from the Assembler?

@sprynmr let synchronizedResolver = (assembler.resolver as! Container).synchronized()
from (https://stackoverflow.com/questions/49687342/crash-container-swift-line-299-container-resolvea-b-entry-serviceentrypro)

I've created a patch: #445. I would really appreciate if somebody could review this! Thanks :)

The PR submitted above #445 appears to fix the issue. As a workaround, I'm using the following extension function until the PR is merged:

extension Assembler {
    public var synchronizedResolver: Resolver {
        let internalResolver = resolver
        if let it = internalResolver as? Container {
            return it.synchronize()
        } else {
            return internalResolver
        }
    }
}