Prevent PDFView from stealing first responder when setting document

AppDelegate.swift

func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
        
        SwizzlePDFDocumentView()
  
        ...
}

SwizzleHelper.m

#import "SwizzleHelper.h"

// found here: https://github.com/defagos/CoconutKit/blob/master/Framework/Sources/Core/HLSRuntime.h 
#import "HLSRuntime.h"
#import <UIKit/UIKit.h>
#import <PDFKit/PDFKit.h>

static BOOL (*s_becomeFirstResponder)(id, SEL) = NULL;

static BOOL swizzle_becomeFirstResponder(id self, SEL _cmd)
{
    if ([self isKindOfClass:NSClassFromString(@"PDFDocumentView")]) {
        return NO;
    }
    return s_becomeFirstResponder(self, _cmd);
}

void SwizzlePDFDocumentView() {
    HLSSwizzleSelector([UIResponder class], @selector(becomeFirstResponder), swizzle_becomeFirstResponder, &s_becomeFirstResponder);
}