Optimize list searches - list

Question

How can I optimize the searches in the list. I have two thousand records. I don't want to do a search through NSPredicate, because I want to pass what is in the field through a function that cleans up the numbers and reduces the letters, before comparing. Can you somehow give a delay so that it does not search immediately but after some time or if the user finishes typing. I also heard about something like Combine, but I have no idea how to use it.
Songbook List
import CoreData
import SwiftUI
struct SongbookView: View {
#State var searchText: String = ""
#Environment(\.managedObjectContext) var managedObjectContext
#FetchRequest(
entity: Song.entity(),
sortDescriptors: [NSSortDescriptor(keyPath: \Song.number, ascending: true)]
) var songs: FetchedResults<Song>
var body: some View {
NavigationView{
VStack{
SearchBar(text: $searchText)
Spacer()
List(songs.filter({searchText.isEmpty ? true : removeNumber(str: $0.content!.lowercased()).contains(searchText.lowercased()) || String($0.number).contains(searchText)}), id:\.objectID) { song in
NavigationLink(destination: DetailView(song: song, isSelected: song.favorite)) {
HStack{
Text("\(String(song.number)). ") .font(.headline) + Text(song.title ?? "Brak tytułu")
if song.favorite {
Spacer()
Image(systemName: "heart.fill")
.accessibility(label: Text("To jest ulubiona pieśń"))
.foregroundColor(.red)
}
}.lineLimit(1)
}
}.id(UUID())
.listStyle(InsetListStyle())
.animation(.default)
}
.padding(.top, 10)
.navigationBarTitleDisplayMode(.inline)
.toolbar {
ToolbarItem(placement: .principal) {
Text("Śpiewnik")
.font(.system(size: 20))
.bold()
}
}
}
}
func removeNumber(str: String) -> String {
var result = str
let vowels: Set<Character> = ["1", "2", "3", "4", "5", "6", "7", "8", "9"]
result.removeAll(where: { vowels.contains($0) })
return result
}
}
Search Bar
import SwiftUI
struct SearchBar: View {
#Binding var text: String
#State var isEditing = false
var body: some View {
HStack {
TextField("Szukaj ...", text: $text)
.padding(7)
.padding(.horizontal, 25)
.background(Color(.systemGray6))
.cornerRadius(8)
.overlay(
HStack {
Image(systemName: "magnifyingglass")
.foregroundColor(.gray)
.frame(minWidth: 0, maxWidth: .infinity, alignment: .leading)
.padding(.leading, 8)
if isEditing {
Button(action: {
self.text = ""
}) {
Image(systemName: "multiply.circle.fill")
.foregroundColor(.gray)
.padding(.trailing, 8)
}
}
}
)
.padding(.horizontal, 10)
.onTapGesture {
self.isEditing = true
}
if isEditing {
Button(action: {
self.isEditing = false
self.text = ""
UIApplication.shared.sendAction(#selector(UIResponder.resignFirstResponder), to: nil, from: nil, for: nil)
}) {
Text("Anuluj")
}
.padding(.trailing, 10)
.transition(.move(edge: .trailing))
.animation(.default)
}
}
}
}

Answer 1

whenever you change the text in your SearchBar (that is every character you type),
the SongbookView is updated
because you are using a binding for text. What you want is to do the update
only once when you press return. There are many ways to do this. A quick way to do this and keep your binding setup, is:
struct SearchBar: View {
#Binding var text: String
#State var txt: String = "" // <--- here a temp var
#State var isEditing = false
var body: some View {
HStack {
TextField("Szukaj ...", text: $txt) // <--- here
.onSubmit {
text = txt // <--- here only update on return press
}
.padding(7)
....
.onAppear {
txt = text // <--- here if needed
}
If you are using ios-14, use
TextField("Szukaj ...", text: $txt, onCommit: { // <--- here
text = txt // <--- here
})