Allow Swift UI to write RxSwift like rx.is Hidden

Allow Swift UI to write RxSwift like rx.is Hidden

I want to be able to bind the display / non-display of Bool value and View!

I implemented the title, so I’ll leave it as a memo.
In RxSwift, you can write as follows.

private let booleanRelay = BehaviorRelay<Bool>(value: false)
// With RxSwift you can write below
booleanRelayText
    .bind(to: label.rx.isHidden)
    .disposed(by: disposeBag)

But in Swift UI you have to write it like this (please let me know if there is a different way to write it)

@State private var boolean = false
if boolean {
    Text("Hello world!")
}

I feel that this writing method has the following problems.

1. The nest becomes deeper.
2. The number of lines increases.
3. I can’t write declaratively.

So I tried to write as follows.

@State private var boolean = false
Text("Hello world!")
    .hidden(boolean)

Now you can show / hide Text according to the boolean value.

Implementation details

The above hidden is implemented as follows.

struct Hidden: ViewModifier {
　　 // Set the value from the parent View
    let hidden: Bool

    func body(content: Content) -> some View {
        VStack {
            if !hidden {
                content
            }
        }
    }
}

extension View {  
    func hidden(_ isHidden: Bool) -> some View {
        ModifiedContent(content: self, modifier: Hidden(hidden: isHidden))
    }
}

For the description of the first structure,

struct Hidden: ViewModifier {
    // Set the value from the parent View
    let hidden: Bool

    func body(content: Content) -> some View {
        if !hidden {
            content
        }
    }
}

I thought it would be okay to write, but I got an error saying Function declares an opaque return type, but has no return statements in its body from which to infer an underlying type.
After a lot of trial and error, I got the above implementation. You may know if you follow the internal implementation, but honestly, I haven’t followed that much.
Is it because there is no View to return when hidden is false?

Summary

There are many cases where SwiftUI cannot be written as expected, so I would like to create an extension like this and deal with it well.
Also, I don’t really understand how to implement it, so I felt that I would like to deepen my understanding little by little.