Swift timeout

[easiwriter]

Is it just me or do others find that the Swift compiler often times out. Obviously it is my code that causes this to happen, but it takes ages to work out what is wrong and I often can't explain to myself why, when I fix it, what the actual problem was. I'll be honest and say I've given up with TCA several times over the past several months, which is a shame because I think the ideas are great. I get the feeling that the source of the time outs lies in the complexity of the TCA macros, but that's just a hunch.

[easiwriter]

Here is my latest example of a timeout. The following code is a simple button:

This compiles OK as part of its view. The code below does not compile but sends the compiler into a screaming loop.

As you can see the second version has one extra line in the action that simply assigns to an editMode environment variable. This seems simple enough. Maybe it's wrong in some way, I don't know, but I am not friends with compilers that fail in this way, because that is what it does - fail.

Surely I'm not he only one who experiences this sort of behaviour?

[mbrandonw]

Hi @easiwriter, this really has nothing to do with TCA and can happen in a vanilla SwiftUI view that is complex enough. Even the screenshots you provide show that adding a line of code that has nothing to do with TCA is causing problems.

All you can do is figure out the various tricks for debugging such problems so that it does not eat up all your time. It is almost always the case that commenting out things until it compiles, and then very slowly adding back lines will narrow down where the problem is. And breaking down very large views into smaller helpers also tends to help.

But regardless, I don't think posting discussions like this to commiserate is helpful. Please try to bring something constructive, such as asking people for their tips on debugging these kinds of problems. Also building up a resource of tips would be very helpful too.

[easiwriter]

Ok, I was just moaning. Sorry. I have only started getting these timeouts since I started using TCA about six months ago. They always happen with views and all the views use TCA if only via Store. The one in my last post makes no sense. Just one innocuous statement the like of which I’ve used in other non-TCA projects. I always identify the source by commenting out bits of code. One thing I’ve noticed is that the fan is often running on my laptop which is a 32gb Intel MacBook Pro. This leads me to suspect that the compiler is short on resources, which is a common reason for failure. Anyway, enough of this. I will endeavor to provide more constructive posts in future.

[easiwriter]

Here's something a little more constructive. I have a view that spawns 4 sheets. Here's the code for the part that invokes the sheets:

With all four of these in the view code Swift timesout. If I comment out any one of the four it compiles, albeit it takes 30 secs for 185 lines of code. Only one of the sheets contains more than 50 lines of code and even that only contains 150 lines.

All four of these sheets are accessed from the parent view. So, my question is how can I better structure the code to stop this happening?

[mbrandonw]

You can move these kinds of things into a private helper function:

struct FeatureView: View {
  let store: StoreOf<Feature>
  var body: some View {
    List {
    }
    .destinations(store: store)
  }
}
extension View {
  fileprivate func destinations(store: StoreOf<Feature>) -> some View {
    self.sheet(item: $store.scope(…)) {
      …
    }
    .sheet(item: $store.scope(…)) {
      …
    }
    .sheet(item: $store.scope(…)) {
      …
    }
    .sheet(item: $store.scope(…)) {
      …
    }
  }
}

[easiwriter]

Thanks for your suggestion, which put me on the right track. I created four modifiers called like this:

The modifiers are invoked from the following view extensions:

And here is one of the modifier functions:

This approach compiles quickly.