@JChen37, You should better start your own thread with including enough context of your case. Not many readers would check the comments added to an old thread.

As already noted, there's no direct equivalent of PHP pack() in any of Apple's frameworks and I have never find any third party libraries implementing PHP pack() in Swift. You may need to implement it all by yourself. When you write questions focused on some specific parts of your implementation with showing your code, many readers would try solving the issues.

What is this method? Can you clarify?

OK. toHex() is this method. The code does not have enough doc nor type hints. But according to the doc of pack(), It is expected to return a binary string. The concept of binary string does not exist in the Swift language. You may need to decide which data type you should return: a binary data (Data is preferred in Swift) or a string?

Do I need to repeat? There is NO binary string in Swift.

Then you need to define how you embed binary data into String.

I think you do not know how to manage concatenating Strings and binary data. No directly exchangeable functionality can be created in Swift as Swift does not have a concept of binary string!!! Do you understand?????

You may need to decide which data type you should return: a binary data (Data is preferred in Swift) or a string? you need to define how you embed binary data into String.

That is not you should look for. What you should look for is the difference of binary data treatment between Swift and PHP.

You said toHex() was the method you wanted and I have shown one solution. That is the end of the topic of the thread. If you want to ask another question, you should start a new thread for that topic. Please include YOUR code when you start a new thread.

Visit Mac App Store with your Mac.

Better start a new thread with clarifying what you want to achieve.

When you show your code, please show it as text using Code Block.

What sort of apps are you developing? The dev forums is a site for developers to talk about developing apps.

Thanks for showing the stack trace. (If it was formatted properly, it would be better.) It shows that it is not a simple recursion thing and is very likely related to SwiftUI things. You may have broken some restrictions of SwiftUI (unfortunately, many of them are not documented clearly) or it may be a bug of SwiftUI. Which is the view causing this crash?