Fix_SwiftUI_BackButton.swift

import SwiftUI
import ObjectiveC

fileprivate var oldIMP: IMP!
fileprivate func swizzle() {
    let ToolbarPlatformDelegate: AnyClass = objc_lookUpClass("_TtC7SwiftUI23ToolbarPlatformDelegate")!
    let method = class_getInstanceMethod(ToolbarPlatformDelegate, #selector(NSToolbarDelegate.toolbar(_:itemForItemIdentifier:willBeInsertedIntoToolbar:)))!
    oldIMP = method_getImplementation(method)
    
    let newIMPFunc: @convention(c) (AnyObject, Selector, NSToolbar, NSToolbarItem.Identifier, ObjCBool) -> NSToolbarItem? = { `self`, _cmd, toolbar, itemIdentifier, flag in
        let oldIMPFunc = unsafeBitCast(oldIMP, to: (@convention(c) (AnyObject, Selector, NSToolbar, NSToolbarItem.Identifier, ObjCBool) -> NSToolbarItem?).self)
        let item = oldIMPFunc(self, _cmd, toolbar, itemIdentifier, flag)
        
        if let item, itemIdentifier.rawValue == "com.apple.SwiftUI.navigationStack.back" {
            // SwiftUI.SwiftUISegmentedControl
            let control = item.view!.subviews.first!.subviews.first! as! NSSegmentedControl
            control.sizeToFit()
            item.view!.setFrameSize(control.bounds.size)
        }
        
        return item
    }
    
    method_setImplementation(method, unsafeBitCast(newIMPFunc, to: IMP.self))
}