Optimizing Performance

import UIKit

class ViewController: UIViewController {
    override func viewDidLoad() {
        super.viewDidLoad()
        // Simulate CPU-intensive task
        let startTime = CFAbsoluteTimeGetCurrent()
        for i in 0..<1_000_000 {
            _ = sqrt(Double(i))
        }
        let timeElapsed = CFAbsoluteTimeGetCurrent() - startTime
        print("Time elapsed: \(timeElapsed)s")
    }
}

func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
    let cell = tableView.dequeueReusableCell(withIdentifier: "CellIdentifier", for: indexPath)
    cell.textLabel?.text = data[indexPath.row].title
    return cell
}

tableView.estimatedRowHeight = 44.0
tableView.rowHeight = UITableView.automaticDimension

class MyViewController: UIViewController {
    @IBOutlet weak var tableView: UITableView!

    override func viewDidLoad() {
        super.viewDidLoad()
        tableView.register(MyCustomCell.self, forCellReuseIdentifier: "MyCell")
    }
}

extension MyViewController: UITableViewDataSource {
    func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let cell = tableView.dequeueReusableCell(withIdentifier: "MyCell", for: indexPath) as! MyCustomCell
        cell.titleLabel.text = "Item \(indexPath.row)"
        return cell
    }
}

class ImageTableViewCell: UITableViewCell {
    @IBOutlet weak var imageView: UIImageView!
    
    lazy var imageLoader = ImageLoader()
    
    func loadImage(for url: URL) {
        imageLoader.loadImage(from: url) { [weak self] image in
            DispatchQueue.main.async {
                self?.imageView.image = image
            }
        }
    }
}

import SDWebImage

let imageView = UIImageView()
imageView.sd_setImage(with: URL(string: "https://example.com/image.jpg"))

import Kingfisher

let imageView = UIImageView()
imageView.kf.setImage(with: URL(string: "https://example.com/image.jpg"))

import Foundation

func performHeavyTask() {
    DispatchQueue.global(qos: .background).async {
        // Simulate heavy computation
        let result = (1...1000000).reduce(0, +)
        
        DispatchQueue.main.async {
            print("Result: \\(result)")
        }
    }
}

performHeavyTask()

// Before: Deep nesting
let containerView = UIView()
let subView1 = UIView()
let subView2 = UIView()
let subView3 = UIView()

containerView.addSubview(subView1)
subView1.addSubview(subView2)
subView2.addSubview(subView3)

// After: Flattened structure
let containerView = UIView()
let subView1 = UIView()
let subView2 = UIView()
let subView3 = UIView()

containerView.addSubview(subView1)
containerView.addSubview(subView2)
containerView.addSubview(subView3)

class CustomView: UIView {
    override init(frame: CGRect) {
        super.init(frame: frame)
        self.isOpaque = true
    }

    required init?(coder: NSCoder) {
        super.init(coder: coder)
        self.isOpaque = true
    }

    override func draw(_ rect: CGRect) {
        // Custom drawing code here
        // Since isOpaque is true, the system assumes the view is fully opaque
    }
}

import SwiftUI

struct ContentView: View {
    @State private var isExpanded = false
    
    var body: some View {
        VStack {
            Button("Toggle") {
                isExpanded.toggle()
            }
            
            if isExpanded {
                Text("Expanded content")
                    .padding()
            }
        }
    }
}

let url = URL(string: "https://api.example.com/data")!
let task = URLSession.shared.dataTask(with: url) { data, response, error in
    guard let data = data else { return }
    // Process the data
}
task.resume()

let config = URLSessionConfiguration.default
config.timeoutInterval = 30
let session = URLSession(configuration: config)
let task = session.dataTask(with: url) { data, response, error in
    // Handle response
}
task.resume()

class ImageCache {
    private let cache = NSCache<NSString, UIImage>()
    
    func image(forKey key: String) -> UIImage? {
        return cache.object(forKey: key as NSString)
    }
    
    func setImage(_ image: UIImage, forKey key: String) {
        cache.setObject(image, forKey: key as NSString)
    }
}

class ViewController: UIViewController {
    @IBOutlet weak var imageView: UIImageView!

    override func viewDidLoad() {
        super.viewDidLoad()
        // Load image only when view is about to appear
        DispatchQueue.main.async {
            self.imageView.image = UIImage(named: "expensiveImage")
        }
    }
}

class AppDelegate: UIResponder, UIApplicationDelegate {
    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
        // Preload assets in background
        DispatchQueue.global(qos: .background).async {
            _ = UIImage(named: "preloadImage")
        }
        return true
    }
}