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Simple Close Button Handling for Flutter Snackbar

Adding a close button to a snackbar in Flutter is simple, however there is one subtlety to be aware of. If the view closes before the snackbar does then you can no longer get the ScaffoldMessenger from context in the close handler. Instead you need to pass the ScaffoldMessenger into the closure so that it remains available after the view closes. Wrong Way This approach will work most of the time, unless the view has already been disposed when the close button is clicked. Since snackbars are often used for errors or other termination handlers it is fairly common for [Read on…]

Success With AWS Web Socket Endpoint Configuration

I had a lot of trouble getting the API Gateway socket management calls to work using the AWS SDK V2 version of the Golang SDK. The problem was that I was not invoking the right endpoint. So that I remember in the future how to do this and to help anyone having similar problems here’s the magic formula I finally learned. Endpoint Value First you need to know the endpoint to use to make calls against. You can either look it up in the AWS console or get it dynamically from the request. I chose to get it from the [Read on…]

Working AWS Websocket JWT Authorizer

I was trying to add JWT authentication to an AWS web socket endpoint and it wasn’t working. My problem was simple and it was even spelled out mentioned in passing somewhere in the AWS docs and it still took me a long time to figure it out. The answer is that only request style authenticators are supported, not token. The docs say that here in that it doesn’t mention a token authorizer and explicitly states that only request is supported here. This post also makes the same point. In Serverless the configuration for the authorizer looks like this: Then a [Read on…]

Connecting Siri to Custom Intents in SwiftUI

Making a custom intent for Siri is pretty simple and there are some good articles on it out there but when I followed them it wasn’t working for me. Specifically asking Siri or invoking a shortcut was returning an error and my Intent handler wasn’t being called. The answer turned out to be really simple once I knew what I was doing. Hopefully this helps someone else. Creating the intent For SwiftUI this article is a good walk through, the Apple documentation is also good. What was missing for me is how Siri knows to invoke your extension in a [Read on…]

Simple HTML Parsing in Swift

I needed to parse some HTML in a SwiftUI project so I could put the content into a Text view. I couldn’t use the HTML partly because of weird behaviour in WKWebView but that’s for another post. This is was a simple case, I didn’t need any structure information from the HTML, just the text with the tags removed. Parsing HTML is always a bit evil so I tend to look for built-in services that can do it for me. Here’s what I found. Using NSAttributedString to load HTML Turns out that NSAttributedString has a way to directly load HTML [Read on…]

Sharing Swift package with WatchOS extension

I was working on a simple iOS app as a small side project and thought it would be fun to have a watch extension for it. Since the bulk of the project involved retrieving and parsing some JSON via a REST call, I wanted to share a package with Swift code between the app and the extension. It turned out to be complicated to figure out how to do that. It’s simple to do in practice so I wanted to document the process for the future. Note: This is not the simplest way to share code. It is the simplest [Read on…]

Missing argument in SwiftUI ForEach

I’ve been experimenting a bit with SwiftUI and ran into an error that it took me an embarrassingly long time to diagnose. The error message is “Missing argument for parameter #1 in call” and it appeared on a ForEach statement in a View. Here’s the cause as well as some troubleshooting steps I wish I’d followed. The SwiftUI Code The change I was trying to make was to the return type of the property stuff.all. I wanted to return a more specialized type to handle some localization conditions. For example, a change like this: As soon as I made the [Read on…]

JSON decoding in Swift Failure

Just ran into this error when trying to decode some JSON in Swift and the error message had me stumped for too long despite being trivial so I thought I’d commit it to memory. The JSON looked like this: And here’s the Swift struct I was trying to use to decode it: The problem is in the declaration of bar in Foo, it is not an array of Bar, it is just a Bar. So the declaration should be: Then this test case will work:

Flutter Null Safety Unit Tests: Late for Tests

Dart added the late keyword as part of their null safety release and it is very useful, particularly for testing. As a quick review null safety means telling the compiler that some variables will never be null. Any variable declared without a question mark following the type declaration is null safe. So String name is null safe while String? name can be null. Given that the question mark is new syntax all code written before null safety was introduced now declares all variables as cannot be null. The new late keyword tells the compiler that although a variable is not [Read on…]

GO Obsolete Dependencies

This article refers to problems that would probably only be seen for those running older versions of GO. If you know all about module management and are running up to date versions of GO with modules then you probably won’t find anything useful here. Up until very recently I was running a pre-module GO version and that bit me. If like me, you haven’t made the switch to modules and some of your dependencies appear to be missing functionality that you’re sure is there, read on. Signs of Trouble It all started with a fairly innocuous error message from the [Read on…]