Foundation Set 2: UIKit Fundamentals (25 Q&A)

class MyViewController: UIViewController {
    
    // 1. INIT - View controller created
    init() {
        super.init(nibName: nil, bundle: nil)
        print("1. init()")
    }
    
    // 2. LOAD VIEW - View is loaded into memory
    override func loadView() {
        super.loadView()
        print("2. loadView()")
        // Override only if creating view programmatically
    }
    
    // 3. VIEW DID LOAD - View loaded, outlets connected
    override func viewDidLoad() {
        super.viewDidLoad()
        print("3. viewDidLoad()")
        // ONE TIME setup: add subviews, configure UI
    }
    
    // 4. VIEW WILL APPEAR - About to be shown
    override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)
        print("4. viewWillAppear")
        // RECURRING: refresh data, start animations
    }
    
    // 5. VIEW DID APPEAR - Now visible
    override func viewDidAppear(_ animated: Bool) {
        super.viewDidAppear(animated)
        print("5. viewDidAppear")
        // Start heavy operations, track analytics
    }
    
    // 6. VIEW WILL DISAPPEAR - About to be hidden
    override func viewWillDisappear(_ animated: Bool) {
        super.viewWillDisappear(animated)
        print("6. viewWillDisappear")
        // Save state, pause operations
    }
    
    // 7. VIEW DID DISAPPEAR - Hidden
    override func viewDidDisappear(_ animated: Bool) {
        super.viewDidDisappear(animated)
        print("7. viewDidDisappear")
        // Stop timers, release resources
    }
    
    // 8. DEINIT - View controller deallocated
    deinit {
        print("8. deinit")
        // Clean up observers, cancel operations
    }
}

override func loadView() {
    // DON'T call super.loadView()
    
    // Create root view
    let customView = CustomView(frame: UIScreen.main.bounds)
    customView.backgroundColor = .white
    
    // Set as view controller's view
    self.view = customView
}

// ❌ WRONG
override func loadView() {
    super.loadView()  // Don't call super!
    self.view.backgroundColor = .red
}

// ✅ CORRECT - use viewDidLoad instead
override func viewDidLoad() {
    super.viewDidLoad()
    view.backgroundColor = .red
}

override func viewDidLoad() {
    super.viewDidLoad()
    
    // ONE-TIME setup
    setupTableView()
    addSubviews()
    setupConstraints()
    registerCells()
}

override func viewWillAppear(_ animated: Bool) {
    super.viewWillAppear(animated)
    
    // RECURRING updates
    refreshData()
    updateNavigationBar()
    startLocationUpdates()
    deselectTableViewRows()
}