Today we'll start off this brand new series on how to build out the YouTube application for iOS. I'll give you guys a quick demo of the application and some of the features/functionality that we'll be writing in Swift. Sit back, relax, and enjoy this first lesson where we'll focus on building out the Home Feed portion of the app!

<div class='filename'>HomeController.swift</div> !codebreak !syntax-highlight class HomeController: UICollectionViewController, UICollectionViewDelegateFlowLayout { override func viewDidLoad() { super.viewDidLoad() navigationItem.title = "Home" collectionView?.backgroundColor = UIColor.whiteColor() collectionView?.registerClass(VideoCell.self, forCellWithReuseIdentifier: "cellId") } override func collectionView(collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int { return 5 } override func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell { let cell = collectionView.dequeueReusableCellWithReuseIdentifier("cellId", forIndexPath: indexPath) return cell } func collectionView(collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAtIndexPath indexPath: NSIndexPath) -> CGSize { return CGSizeMake(view.frame.width, 200) } func collectionView(collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumLineSpacingForSectionAtIndex section: Int) -> CGFloat { return 0 } } !codebreak <div class='filename'>VideoCell.swift</div> !codebreak !syntax-highlight class VideoCell: UICollectionViewCell { override init(frame: CGRect) { super.init(frame: frame) setupViews() } let thumbnailImageView: UIImageView = { let imageView = UIImageView() imageView.backgroundColor = UIColor.blueColor() imageView.image = UIImage(named: "taylor_swift_blank_space") return imageView }() let userProfileImageView: UIImageView = { let imageView = UIImageView() imageView.backgroundColor = UIColor.greenColor() return imageView }() let separatorView: UIView = { let view = UIView() view.backgroundColor = UIColor.blackColor() return view }() let titleLabel: UILabel = { let label = UILabel() label.backgroundColor = UIColor.purpleColor() label.translatesAutoresizingMaskIntoConstraints = false return label }() let subtitleTextView: UITextView = { let textView = UITextView() textView.backgroundColor = UIColor.redColor() textView.translatesAutoresizingMaskIntoConstraints = false return textView }() func setupViews() { addSubview(thumbnailImageView) addSubview(separatorView) addSubview(userProfileImageView) addSubview(titleLabel) addSubview(subtitleTextView) addConstraintsWithFormat("H:|-16-[v0]-16-|", views: thumbnailImageView) addConstraintsWithFormat("H:|-16-[v0(44)]", views: userProfileImageView) //vertical constraints addConstraintsWithFormat("V:|-16-[v0]-8-[v1(44)]-16-[v2(1)]|", views: thumbnailImageView, userProfileImageView, separatorView) addConstraintsWithFormat("H:|[v0]|", views: separatorView) //top constraint addConstraint(NSLayoutConstraint(item: titleLabel, attribute: .Top, relatedBy: .Equal, toItem: thumbnailImageView, attribute: .Bottom, multiplier: 1, constant: 8)) //left constraint addConstraint(NSLayoutConstraint(item: titleLabel, attribute: .Left, relatedBy: .Equal, toItem: userProfileImageView, attribute: .Right, multiplier: 1, constant: 8)) //right constraint addConstraint(NSLayoutConstraint(item: titleLabel, attribute: .Right, relatedBy: .Equal, toItem: thumbnailImageView, attribute: .Right, multiplier: 1, constant: 0)) //height constraint addConstraint(NSLayoutConstraint(item: titleLabel, attribute: .Height, relatedBy: .Equal, toItem: self, attribute: .Height, multiplier: 0, constant: 20)) //top constraint addConstraint(NSLayoutConstraint(item: subtitleTextView, attribute: .Top, relatedBy: .Equal, toItem: titleLabel, attribute: .Bottom, multiplier: 1, constant: 8)) //left constraint addConstraint(NSLayoutConstraint(item: subtitleTextView, attribute: .Left, relatedBy: .Equal, toItem: userProfileImageView, attribute: .Right, multiplier: 1, constant: 8)) //right constraint addConstraint(NSLayoutConstraint(item: subtitleTextView, attribute: .Right, relatedBy: .Equal, toItem: thumbnailImageView, attribute: .Right, multiplier: 1, constant: 0)) //height constraint addConstraint(NSLayoutConstraint(item: subtitleTextView, attribute: .Height, relatedBy: .Equal, toItem: self, attribute: .Height, multiplier: 0, constant: 20)) } required init?(coder aDecoder: NSCoder) { fatalError("init(coder:) has not been implemented") } } !codebreak <div class='filename'>UIView extension</div> !codebreak !syntax-highlight extension UIView { func addConstraintsWithFormat(format: String, views: UIView...) { var viewsDictionary = [String: UIView]() for (index, view) in views.enumerate() { let key = "v\(index)" view.translatesAutoresizingMaskIntoConstraints = false viewsDictionary[key] = view } addConstraints(NSLayoutConstraint.constraintsWithVisualFormat(format, options: NSLayoutFormatOptions(), metrics: nil, views: viewsDictionary)) } } !codebreak <div class='filename'>AppDelegate.swift</div> !codebreak !syntax-highlight func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool { window = UIWindow(frame: UIScreen.mainScreen().bounds) window?.makeKeyAndVisible() let layout = UICollectionViewFlowLayout() window?.rootViewController = UINavigationController(rootViewController: HomeController(collectionViewLayout: layout)) return true }