I'm using ScrollView to display my course list, and each card in the list, named 'CourseCardView' as shown in the code. When I test it on both the simulator and a physical device, I notice that scrolling is not smooth and feels laggy. I'm not sure how to address this issue.
Here is my code:
//
// CourseListView.swift
// LexueSwiftUI
//
// Created by bobh on 2023/9/3.
//
import SwiftUI
struct CourseCardView: View {
let cardHeight: CGFloat = 150
let cardCornelRadius: CGFloat = 10
let cardHorizontalPadding: CGFloat = 10
@State var courseName = "course name"
@State var courseCategory = "category name"
@State var progress = 66
var body: some View {
ZStack {
Image("default_course_bg2")
.resizable()
.blur(radius: 5, opaque: true)
.cornerRadius(cardCornelRadius)
.padding(.horizontal, cardHorizontalPadding)
.frame(height: cardHeight)
Color.white
.cornerRadius(cardCornelRadius)
.padding(.horizontal, cardHorizontalPadding)
.frame(height: cardHeight)
.opacity(0.1)
VStack(alignment: .leading, spacing: 2) {
Spacer()
Text(courseName)
.bold()
.font(.title)
.foregroundColor(.white)
.lineLimit(1)
.shadow(color: .black.opacity(0.5), radius: 5, x: 0, y: 2)
.padding(.leading, 10)
Text(courseCategory)
.bold()
.font(.headline)
.foregroundColor(.white)
.lineLimit(1)
.shadow(color: .black.opacity(0.5), radius: 5, x: 0, y: 2)
.padding(.leading, 10)
.padding(.bottom, 5)
ProgressView(value: Double(progress) / 100.0)
.padding(.horizontal, 10)
.padding(.bottom, 10)
.accentColor(.white)
.shadow(color: .black.opacity(0.3), radius: 5, x: 0, y: 2)
}
.frame(height: cardHeight)
.frame(maxWidth: .infinity, alignment: .leading)
.padding(.horizontal, cardHorizontalPadding)
VStack {
HStack {
Spacer()
Button(action: {
}) {
Image(systemName: "star")
.foregroundColor(.white)
.font(.system(size: 24).weight(.regular))
.shadow(color: .black.opacity(0.3), radius: 5, x: 0, y: 2)
}
.padding(.trailing, 10)
.padding(.top, 10)
}
Spacer()
}
.frame(height: cardHeight)
.frame(maxWidth: .infinity, alignment: .leading)
.padding(.horizontal, cardHorizontalPadding)
}
.shadow(color: .black.opacity(0.3), radius: 5, x: 0, y: 2)
}
}
private struct ListView: View {
@Binding var courses: [CourseShortInfo]
@Binding var isRefreshing: Bool
@Environment(\.refresh) private var refreshAction
@ViewBuilder
var refreshToolbar: some View {
if let doRefresh = refreshAction {
if isRefreshing {
ProgressView()
} else {
Button(action: {
Task{
await doRefresh()
}
}) {
Image(systemName: "arrow.clockwise")
}
}
}
}
var body: some View {
VStack {
ScrollView(.vertical) {
LazyVStack(spacing: 20){
ForEach(courses) { item in
CourseCardView(courseName: item.shortname!, courseCategory: item.coursecategory!, progress: item.progress!)
.listRowSeparator(.hidden)
}
}
}
.toolbar {
refreshToolbar
}
}
}
}
struct CourseListView: View {
@State private var courseList = GlobalVariables.shared.courseList
@State var isRefreshing: Bool = false
@State var searchText: String = ""
func testRefresh() async {
Task {
isRefreshing = true
Thread.sleep(forTimeInterval: 1.5)
withAnimation {
isRefreshing = false
}
}
}
var body: some View {
NavigationView {
VStack {
ListView(courses: $courseList, isRefreshing: $isRefreshing)
.refreshable {
print("refresh")
await testRefresh()
}
}
.searchable(text: $searchText, prompt: "Search the course")
.navigationTitle("Course")
.navigationBarTitleDisplayMode(.large)
}
}
}
struct CourseListView_Previews: PreviewProvider {
static var previews: some View {
CourseListView()
}
}
The global variable code:
import Foundation
import SwiftUI
class GlobalVariables {
static let shared = GlobalVariables()
@Published var isLogin = true
@Published var courseList: [CourseShortInfo] = [
CourseShortInfo(id: 11201, shortname: "数据结构与C++程序设计", progress: 66, coursecategory: "自动化学院"),
CourseShortInfo(id: 11202, shortname: "数值分析", progress: 20, coursecategory: "数学学院"),
CourseShortInfo(id: 11203, shortname: "数据结构与C++程序设计", progress: 66, coursecategory: "自动化学院"),
CourseShortInfo(id: 11204, shortname: "数值分析", progress: 20, coursecategory: "数学学院"),
CourseShortInfo(id: 11205, shortname: "数据结构与C++程序设计", progress: 66, coursecategory: "自动化学院"),
CourseShortInfo(id: 11206, shortname: "数值分析", progress: 20, coursecategory: "数学学院"),
CourseShortInfo(id: 11207, shortname: "数据结构与C++程序设计", progress: 66, coursecategory: "自动化学院"),
CourseShortInfo(id: 11208, shortname: "数值分析", progress: 20, coursecategory: "数学学院"),
CourseShortInfo(id: 11209, shortname: "数据结构与C++程序设计", progress: 66, coursecategory: "自动化学院"),
CourseShortInfo(id: 11210, shortname: "数值分析", progress: 20, coursecategory: "数学学院")
]
var debugMode = true
private init() {
}
}
