Run CKQueryOperation with results from previous CKQueryOperation

Hi,

I have an app that is a shopping list. I can store prices per product and vendor in my app, the model is

Product
Vendor
Price

One product can have multiple prices from different vendors.

I store the price information with references to the product and vendor (CKRecord.Reference).

Now I am using the below to fetch all the prices related to a product:

Code Block 
public func fetchDataByProduct(product: Product, completionHandler: @escaping (Bool) -> Void){
		self.pricesBuffer = []
		let cloudContainer = CKContainer.init(identifier: "iCloud.XYZ")
		let publicDatabase = cloudContainer.publicCloudDatabase
		let reference = CKRecord.Reference(recordID: product.recordID, action: .deleteSelf)
		let predicate = NSPredicate(format: "priceToProduct == %@", reference)
		let query = CKQuery(recordType: "Price", predicate: predicate)
		let operation = CKQueryOperation(query: query)
		operation.recordFetchedBlock = { record in
			let price = Price()
			price.recordID = record.recordID
			price.grossPrice = record.object(forKey: "grossPrice") as? Double
			let dummy = record.object(forKey: "priceToVendor") as! CKRecord.Reference
			price.vendorRecordID = dummy.recordID
			self.pricesBuffer.append(price)
		}
		operation.queryCompletionBlock = { [unowned self] (cursor, error) in
			self.pricesBuffer.forEach({price in
				price.retrieveVendor()
			})
			DispatchQueue.main.async {
				if error == nil {
					self.prices = self.pricesBuffer
					completionHandler(true)
				} else {
				}
			}
		}
		publicDatabase.add(operation)
	}

My problem is now that I cannot retrieve the vendor name which is part of the Vendor object (Vendor.name).

I have tried to loop over the pricesBuffer and run this one per price but the problem seems to be that CloudKit first completes the initial request to fetchDataByProduct() and then afterwards fetches the vendor data but then its too late because that updated data does not get pushed to my View (SwiftUI).

Code Block 
publicDatabase.fetch(withRecordID: self.vendorRecordID, completionHandler:  {[unowned self] record, error in
			if let record = record {
				print(record)
				self.vendor.recordID = record.recordID
				self.vendor.name = record["name"] as! String
				print(self.vendor.name)
			}
		})

Any ideas how to solve this? I believe I have to add a second CKQueryOperation to the mix and use the .addDependency() but I cannot wrap my head around how that should look like in the end.

Max