I have a field where the user begins typing the name of a prescription drug and after 3 characters it searches through a 4.5mb JSON file containing over 36k entries. There are only two fields in the struct holding the decoded JSON (name and id) and I am doing a simple ForEach. However it is extremely slow and I need to make it real-time. This is a local JSON file in the app (i.e. I am not calling to an external URL).
There are a few issues I need to resolve:
- I need to make this as responsive as possible
- I need to return the results sorted by the name, but including numbers (i.e. Tylenol 50MG should come before Tylenol 100MG).
For issue #2 I tried using compare, which works but slowed things down even further, as follows:
var allDrugsSorted: [Mod_Prescription_DrugsList] {
return Mod_Prescription_DrugsList.allDrugs.sorted { first, second in
first.name.compare(second.name, options: .numeric) == .orderedAscending
} // End Return
}
This is my ForEach:
if isFocused == .prescription_name &&
viewModel.prescriptionName.count >= 3 {
ForEach(
viewModel.allDrugsSorted.filter {
$0.name
.lowercased()
.hasPrefix(
viewModel.prescriptionName.lowercased()
)
}.prefix(5), id: \.self) { prescription in
Button {
isFocused = nil
} label: {
VStack(alignment: .leading) {
Text(LocalizedStringKey(prescription.name))
}
.frame(maxWidth: .infinity, alignment: .leading)
} // End Label
.contentShape(Rectangle())
.padding()
} // End ForEach
} // End If
I already tried the .id(UUID()) trick and it did nothing to help.
This is the struct in which I am loading the JSON:
struct Mod_Prescription_DrugsList: Codable, Hashable {
let rxcui: String
let name: String
static let allDrugs = Bundle.main.decode([Mod_Prescription_DrugsList].self, from: "Drugs.json")
static let example = allDrugs[0]
}
This is the decode extension on Bundle:
extension Bundle {
func decode<T: Decodable>(
_ type: T.Type,
from file: String,
dateDecodingStrategy: JSONDecoder.DateDecodingStrategy = .deferredToDate,
keyDecodingStrategy: JSONDecoder.KeyDecodingStrategy = .useDefaultKeys
) -> T {
guard let url = self.url(
forResource: file,
withExtension: nil
) else {
fatalError("Failed to locate \(file) in bundle.")
}
guard let data = try? Data(
contentsOf: url
) else {
fatalError("Failed to load \(file) from bundle.")
}
let decoder = JSONDecoder()
decoder.dateDecodingStrategy = dateDecodingStrategy
decoder.keyDecodingStrategy = keyDecodingStrategy
do {
return try decoder.decode(T.self, from: data)
} catch DecodingError.keyNotFound(let key, let context) {
fatalError("Failed to decode \(file) from bundle due to missing key '\(key.stringValue)' - \(context.debugDescription)")
} catch DecodingError.typeMismatch(_, let context) {
fatalError("Failed to decode \(file) from bundle due to type mismatch - \(context.debugDescription)")
} catch DecodingError.valueNotFound(let type, let context) {
fatalError("Failed to decode \(file) from bundle due to missing \(type) value - \(context.debugDescription)")
} catch DecodingError.dataCorrupted(_) {
fatalError("Failed to decode \(file) from bundle because it appears to be invalid JSON")
} catch {
fatalError("Failed to decode \(file) from bundle - \(error.localizedDescription)")
}
}
}
I also tried creating a decoded array in the view model on init and though it speeds things up a little, it's still not great, and it's unusable because the view now takes almost a minute to load. self.allDrugsArray is an @Published var in the view model. Here's the function I wrote:
func getAllDrugs() {
let sortedDrugs = Mod_Prescription_DrugsList.allDrugs.sorted { first, second in
first.name.compare(second.name, options: .numeric) == .orderedAscending
}
sortedDrugs.forEach { drug in
self.allDrugsArray.append(drug)
}
}
CodePudding user response：
You really need to restructure this. You load your List, sort it and filter it every time your View needs to update. You should keep this list in a sorted state in Memory and filter it as you need.
Following architecture should work:
import Combine
class Viewmodel: ObservableObject{
//used to show the results
@Published var sortedAndFiltered: [Mod_Prescription_DrugsList] = []
//used to store the list
@Published var sorted: [Mod_Prescription_DrugsList] = []
//filter string
@Published var prescriptionName: String = ""
//Load, sort and assign the items here
init(){
$prescriptionName
.debounce(for: 0.4, scheduler: RunLoop.main) //Wait for user to stop typing
.receive(on: DispatchQueue.global()) // perform filter on background
.map{[weak self] filterString in
guard filterString.count > 3, let self = self else{
return []
}
//n apply the filter
return self.sorted.filter {
$0.name
.lowercased()
.hasPrefix(
filterString.lowercased()
)
}
}
.receive(on: RunLoop.main) // switch back to uithread
.assign(to: &$sortedAndFiltered)
}
func load(){
sorted = Mod_Prescription_DrugsList.allDrugs.sorted { first, second in
first.name.compare(second.name, options: .numeric) == .orderedAscending
}
}
}
struct ContentView: View{
@FocusState var isFocused: Bool
@StateObject private var viewmodel: Viewmodel = Viewmodel()
var body: some View{
VStack{
if isFocused &&
viewmodel.sortedAndFiltered.count >= 3 {
ForEach(viewmodel.sortedAndFiltered, id: \.self) { prescription in
Button {
isFocused = false
} label: {
VStack(alignment: .leading) {
Text(LocalizedStringKey(prescription.name))
}
.frame(maxWidth: .infinity, alignment: .leading)
} // End Label
.contentShape(Rectangle())
.padding()
} // End ForEach
} // End If
}.onAppear{ // I had to add a VStack to be able to do this just add it to the element surrounding your ForEach
// If list is empty load it in the background, so your app stays responsive
if viewmodel.sorted.count == 0{
Task{
viewmodel.load()
}
}
}
}
}
This is a more generalized approach so you will have to integrate this solution in your work. I have commented as much as I thought would be necessary. If you have questions don´t hessitate to ask. I didn´t have the chance to test this, so there may be some minor things to adress.