Swift UICollectionViewをコードでつくる

UICollectionViewをコードでつくります

UICollectionViewDelegate, UICollectionViewDataSource UICollectionViewDelegateFlowLayout　をUIViewController 内で実装します UIは, xibや, storyboardを使わずすべてコードで実装します セルやフッターなどのUIコードは省略します.

class ViewController : UIViewController, UICollectionViewDelegate, UICollectionViewDataSource, UICollectionViewDelegateFlowLayout {
    private let barSize : CGFloat = 44.0
    private let kCellReuse : String = "PackCell"
    private let kCellheaderReuse : String = "PackHeader"
    private var collectionView : UICollectionView = UICollectionView(frame: CGRectZero, collectionViewLayout: UICollectionViewFlowLayout())   // Initialization
 
    override func viewDidLoad() {
        super.viewDidLoad()
 
        // Collection
        self.collectionView.delegate = self     // delegate  :  UICollectionViewDelegate
        self.collectionView.dataSource = self   // datasource  : UICollectionViewDataSource
        self.collectionView.backgroundColor = UIColor.clearColor()
 
        // Register parts(header and cell
        self.collectionView.registerClass(PackViewCell.self, forCellWithReuseIdentifier: kCellReuse) // UICollectionViewCell
        self.collectionView.registerClass(PackCollectionSectionView.self, forSupplementaryViewOfKind: UICollectionElementKindSectionHeader, withReuseIdentifier: kCellheaderReuse)  // UICollectionReusableView
         
        self.view.addSubview(self.collectionView)
    }
 
    override func viewWillLayoutSubviews() {
        let frame = self.view.frame
        self.collectionView.frame = CGRectMake(frame.origin.x, frame.origin.y + barSize, frame.size.width, frame.size.height - barSize)
    }
 
    // MARK: UICollectionViewDelegate, UICollectionViewDataSource
    func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {
        var cell : PackViewCell = collectionView.dequeueReusableCellWithReuseIdentifier(kCellReuse, forIndexPath: indexPath) as PackViewCell
        return cell    // Create UICollectionViewCell
    }
 
    func numberOfSectionsInCollectionView(collectionView: UICollectionView) -> Int {
        return 1  // Number of section
    }
 
    func collectionView(collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        var res = 0
        switch(section) {
        case 0:
            res = 4  // Number of cell per section(section 0)
            break
        default:
            res = 0
            break
        }
        return res
    }
 
    func collectionView(collectionView: UICollectionView, didSelectItemAtIndexPath indexPath: NSIndexPath) {
        collectionView.deselectItemAtIndexPath(indexPath, animated: false) 
        // Select operation
    }
 
    func collectionView(collectionView: UICollectionView, viewForSupplementaryElementOfKind kind: String, atIndexPath indexPath: NSIndexPath) -> UICollectionReusableView {
        var reusableView : UICollectionReusableView? = nil
         
        // Create header
        if (kind == UICollectionElementKindSectionHeader) {
            // Create Header
            var headerView : PackCollectionSectionView = collectionView.dequeueReusableSupplementaryViewOfKind(UICollectionElementKindSectionHeader, withReuseIdentifier: kCellheaderReuse, forIndexPath: indexPath) as PackCollectionSectionView
             
            reusableView = headerView
        }
        return reusableView!
    }
 
    // MARK: UICollectionViewDelegateFlowLayout
    func collectionView(collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAtIndexPath indexPath: NSIndexPath) -> CGSize {
        return CGSize(width: 90, height: 90) // The size of one cell
    }
 
    func collectionView(collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, referenceSizeForHeaderInSection section: Int) -> CGSize {
        return CGSizeMake(self.view.frame.width, 90)  // Header size
    }
 
    func collectionView(collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, insetForSectionAtIndex section: Int) -> UIEdgeInsets {
        let frame : CGRect = self.view.frame
        let margin  = (frame.width - 90 * 3) / 6.0
        return UIEdgeInsetsMake(10, margin, 10, margin) // margin between cells
    }
}

UICollectionViewDelegateFlowLayout の実装でセルのサイズや, ヘッダーのサイズ, セル間のマージンなどを決めています UICollectionViewDelegate, 実装していれば読み込まれるはずです コードそのものは, UITableViewの実装によく似ています. 行やセクションのナンバーから, セルを引っ張りだすことなど 違いは , レイアウトが柔軟なこと, サイズを返すところで行ごとにサイズを変更できます