Grid View with View Builder SwiftUI

GridView.swift

import SwiftUI

struct GridView: View {
    let columns: Int
    let columnAlignment: VerticalAlignment
    let rowAlignment: HorizontalAlignment
    let rowSpacing: CGFloat?
    let columnSpacing: CGFloat?

    let content: [AnyView]

    var body: some View {
        let rows = content.chunked(into: columns)
        return VStack(alignment: self.rowAlignment, spacing: self.rowSpacing) {
            ForEach(0..<rows.count) { row in
                HStack(alignment: self.columnAlignment, spacing: self.columnSpacing) {
                    ForEach(0..<rows[row].count) { column in
                        rows[row][column]
                    }
                }
            }
        }
    }
}

extension GridView {

    init<Content: View>(columns: Int,
                        columnAlignment: VerticalAlignment = .center,
                        rowAlignment: HorizontalAlignment = .center,
                        rowSpacing: CGFloat? = nil,
                        columnSpacing: CGFloat? = nil,
                        @ViewBuilder content: () -> Content) {

        self.init(columns: columns,
                  columnAlignment: columnAlignment,
                  rowAlignment: rowAlignment,
                  rowSpacing: rowSpacing,
                  columnSpacing: columnSpacing,
                  content: components(in: content()))
    }

}

extension Array {
    func chunked(into size: Int) -> [[Element]] {
        stride(from: 0, to: count, by: size).map {
            Array(self[$0 ..< Swift.min($0 + size, count)])
        }
    }
}

reflection.swift

import Runtime
import SwiftUI

protocol AnyViewStorageBase {
    func render() -> AnyView
}

struct AnyViewStorage<Content : View>: AnyViewStorageBase {
    let view: Content

    func render() -> AnyView {
        return AnyView(view)
    }
}

protocol Decomposable {
    func decompose() -> [AnyView]
}

extension TupleView: Decomposable {

    func decompose() -> [AnyView] {
        let mirror = Mirror(reflecting: self)
        let tuple = mirror.children.first!.value
        let tupleMirror = Mirror(reflecting: tuple)
        return tupleMirror.children.flatMap { anyViews(from: $0.value) }
    }

}

extension ForEach: Decomposable where Content: View {

    func decompose() -> [AnyView] {
        // TODO: Figure out how the updates should happen...
        return data.map { AnyView(content($0)) }
    }

}

extension HStack: Decomposable {

    func decompose() -> [AnyView] {
        return [AnyView(self)]
    }

}

extension ZStack: Decomposable {

    func decompose() -> [AnyView] {
        return [AnyView(self)]
    }

}

extension VStack: Decomposable {

    func decompose() -> [AnyView] {
        return [AnyView(self)]
    }

}

func components<Content: View>(in view: Content) -> [AnyView] {
    if let decomposable = view as? Decomposable {
        return decomposable.decompose()
    }
    return [AnyView(view)]
}

func anyViews(from view: Any) -> [AnyView] {
    if let view = view as? Decomposable {
        return view.decompose()
    }
    return [anyViewStorage(from: view).render()]
}

func anyViewStorage(from view: Any) -> AnyViewStorageBase {
    let genericType = type(of: view)
    let pointer = unsafeBitCast(genericType, to: UnsafeRawPointer.self)
    var symbolInfo = Dl_info()
    dladdr(pointer, &symbolInfo)

    guard let mangledGenericTypeName = symbolInfo.dli_sname.map({ String(cString: $0) })?.dropFirst(2).dropLast()
        else { fatalError() }

    // Warning this is the module name. You would have to change it to yours to run
    let mangledName = "8GridTest14AnyViewStorageVy\(mangledGenericTypeName)G"
    let typePointer = mangledName.cString(using: .utf8)?.withUnsafeBytes { buffer -> UnsafeRawPointer? in
        let casted = buffer.baseAddress!.assumingMemoryBound(to: Int8.self)
        return swift_getTypeByMangledNameInContext(casted, Int32(mangledName.count), nil, nil)
    }
    guard let type = typePointer.map({ unsafeBitCast($0, to: Any.Type.self) }) else {
        fatalError()
    }

    return try! createInstance(of: type) { _ in view } as! AnyViewStorageBase
}

@_silgen_name("swift_getTypeByMangledNameInContext")
func swift_getTypeByMangledNameInContext(
    _ typeNameStart: UnsafePointer<Int8>,
    _ typeNameLength: Int32,
    _ context: UnsafeRawPointer?,
    _ genericArgs: UnsafePointer<UnsafeRawPointer?>?
) -> UnsafeRawPointer?