When i select button its position keep changes why? in SwiftUI

Code: I just want tick on selected button view and need that selected button schoolCode but my code i got check mark also and selected button code also but if i select button its position changes.. if i select 3rd button then it comes to 2nd place like that… please fix this error

 ScrollView(.horizontal, showsIndicators: false) {
         HStack {
                 if let retrievedArray = UserDefaults.standard.stringArray(forKey: "SavedSchoolCodes") {
                    let uniqueItems = Array(Set(retrievedArray))
                    
                    ForEach(uniqueItems, id: \.self) { item in
                                    if let school = schoolList.first(where: { $0.schoolCode == item }) {
                     Button {
                      viewModel.schoolCode = school.schoolCode ?? ""
                     } label: {
                     ZStack {
                         let correctedPhotoURL = school.logo?.replacingOccurrences(of: "//SchImg", with: "/SchImg") ?? ""        
                     VStack {
                                                    
                      URLImageView(url: correctedPhotoURL, placeholder: "NoProfilePic", width: 50, height: 50)
                                                        
                     .clipShape(Circle())
                     .padding(.bottom, 4)                                                        
                     Text(school.schoolCode ?? "")
                     .font(.headline)
                     .foregroundColor(.black)
                     }
                     .frame(width: 100, height: 120)
                     .background(Color.gray.opacity(0.2))
                     .cornerRadius(10)
                                           
                     RoundedRectangle(cornerRadius: 10)
                                                    
                     .stroke(viewModel.schoolCode == school.schoolCode ? Color.green : Color.clear, lineWidth: 2)
                     .frame(width: 100, height: 120)
                    
                     if viewModel.schoolCode == school.schoolCode 
                      {
                                                    
                       Image(systemName: "checkmark.circle.fill")
                       .resizable()
                       .frame(width: 20, height: 20)
                       .foregroundColor(.green)
                       .offset(x: 35, y: -45)
                       }
                  }
                  }
                  .padding(5)
                  } else {
                    Text("\(item),")
                          }
                  }
                  } else {
                          Text("No array found in UserDefaults.")
                            }
                        }
                        .padding(.horizontal)
      }

o/p: when i select i just want checkmark thats it.. please guide to fix change position.

>Solution :

You are converting the list of school codes to a Set, then you iterate over the set and find the corresponding School for each code.

A Set is an unordered container. The ordering of the schools in your view is therefore unpredictable and indeed it seems to change when the view is re-rendered to show the selected school.

Try sorting the array that you create from the Set:

let uniqueItems = Array(Set(retrievedArray)).sorted()