UITableView freezes till loop complete - ios

Question

I am using this code to search text in Database tables:
func runSearch(_ pattern: String) {
for book in selectedBooks {
let path = Bundle.main.path(forResource: "library", ofType: "sqlite")!
let sqlState = "select * from \(book.name)"
guard
let db = FMDatabase(path: path), db.open(),
let result = db.executeQuery(sqlState, withArgumentsIn: [])
else { return }
while result.next() {
RunLoop.current.run(mode: .default, before: .distantPast)
let pageID = result.long(forColumn: "Id")
let pageText = result.string(forColumn: "page_text") ?? ""
if isMatches(regex: pattern, in: pageText) {
dataSource.append(dbItem(id: pageID, text: pageText))
resultsLabel.text = "Results count: " + dataSource.count.description
let indexPath = IndexPath(row: dataSource.count - 1, section: 0)
tableView.insertRows(at: [indexPath], with: .automatic)
}
}
}
}
func isMatches(regex: String, in str: String) -> Bool {
do {
let regex = try NSRegularExpression(pattern: regex)
let matches = regex.matches(in: str, range: NSRange(location: 0, length: str.count))
return matches.count != 0
} catch {
print("Something went wrong! Error: \(error.localizedDescription)")
}
return false
}
I have over 40 books to search through. And the search is done fine, but the "UITableView" freezes until the search is complete. I want to allow the user to scroll through this table and choose what result he wants to display while searching.
Can anyone help me with this, please?

Answer 1

You can make an asynchronous function where you do all the work and after the function ends call tableView.reloadData. Also, you can not insert rows after every loop but when the whole loop ends and you have the right data in your data source then reload data to your table view to refresh it with the new data.