collection的简单使用

import UIKit
//与tableview极其相似，可以互相借鉴
class ViewController: UIViewController,UICollectionViewDelegate, UICollectionViewDataSource {
    
    var collectionview : UICollectionView!
    override func viewDidLoad() {
        super.viewDidLoad()
        let layout = UICollectionViewFlowLayout()//开启自动布局
        layout.itemSize = CGSize(width: self.view.frame.width-20, height: 200)//应该先设置cell的大小
        layout.scrollDirection = .Horizontal//设置滑动的方向，也是cell依次摆放的顺序（下滑横放，右滑竖放）
        layout.minimumLineSpacing = 20//设置上下cell的最小间距（注意：设置的是最小间距，不能设定死的间距，会根据cell的大小摆放，下滑有效，左右滑动没有效果）
        layout.minimumInteritemSpacing = 20//设置左右cell的最小间距，当cell充满整个屏幕宽度时，设置无效
        layout.sectionInset = UIEdgeInsets(top: 20, left: 10, bottom: 10, right: 10)//设置section上下左右的间隙
        
        //设置collection的位置大小
        collectionview = UICollectionView(frame: self.view.bounds, collectionViewLayout: layout)
        collectionview.dataSource = self//使collection关联类的代理
        collectionview.delegate = self
        collectionview.pagingEnabled = true//使滑动翻页
        collectionview.backgroundColor = UIColor.whiteColor()
        
        // 注册cell和header／footer
        collectionview.registerClass(UICollectionViewCell.self, forCellWithReuseIdentifier: "cell")//注册cell
        self.view.addSubview(collectionview)
        
        collectionview.registerClass(UICollectionReusableView.self, forSupplementaryViewOfKind: UICollectionElementKindSectionHeader, withReuseIdentifier: "header")
        collectionview.registerClass(UICollectionReusableView.self, forSupplementaryViewOfKind: UICollectionElementKindSectionFooter, withReuseIdentifier: "footer")
        
        //开启定时器
        NSTimer.scheduledTimerWithTimeInterval(1, target: self, selector: #selector(didTime(_:)), userInfo: nil, repeats: true)
    }
    func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {
        let cell = collectionView.dequeueReusableCellWithReuseIdentifier("cell", forIndexPath: indexPath)
        //设置单双cell的颜色
        if indexPath.item % 2 == 0 {
            cell.contentView.backgroundColor = UIColor.redColor()
        }
        else {
            cell.contentView.backgroundColor = UIColor.blueColor()
        }
        return cell
    }
    //设置返回section的个数
    func collectionView(collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        return 5
    }
    func collectionView(collectionView: UICollectionView, didSelectItemAtIndexPath indexPath: NSIndexPath) {
        print("\(indexPath.row)\(indexPath.item)")
    }
    //    func numberOfSectionsInCollectionView(collectionView: UICollectionView) -> Int {
    //        return 4
    //    }//设置collection的个数
    
    //创建一个计时器，使页面实现自动切换
    func didTime(timer : NSTimer){
        let offset = collectionview.contentOffset
        //根据位置获取Cell（根据偏移量去找下一个cell，只要坐标在下一个cell视图中都可以）
        let indexPath = collectionview.indexPathForItemAtPoint(CGPoint(x: offset.x + 10, y: 20))
        //判断切换页面时下一个cell的下标
        if indexPath!.item == 3{
            collectionview.scrollToItemAtIndexPath(NSIndexPath(forItem: 0,inSection: 0), atScrollPosition: .Left, animated: false)
            
        }
        else{
            collectionview.scrollToItemAtIndexPath(NSIndexPath(forItem: indexPath!.item+3,inSection: 0), atScrollPosition: .Left, animated: true)
        }
    }
    
    //头尾的创建
//        func collectionView(collectionView: UICollectionView, viewForSupplementaryElementOfKind kind: String, atIndexPath indexPath: NSIndexPath) -> UICollectionReusableView {
//            if kind == UICollectionElementKindSectionHeader{
//                let header = collectionview.dequeueReusableSupplementaryViewOfKind(UICollectionElementKindSectionHeader, withReuseIdentifier: "header", forIndexPath: indexPath)
//                header.backgroundColor = UIColor.greenColor()
//                return header
//            }
//            else{
//    
//                let footer = collectionview.dequeueReusableSupplementaryViewOfKind(UICollectionElementKindSectionFooter, withReuseIdentifier: "footer", forIndexPath: indexPath)
//                footer.backgroundColor = UIColor.grayColor()
//                return footer
//    
//            }
//        }
    //设置下一个cell的大小
//        func collectionView(collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAtIndexPath indexPath: NSIndexPath) -> CGSize {
//            return CGSize(width: 10 * (indexPath.item + 1), height: 10 * (indexPath.item + 1))
//        }
    //设置头尾的大小，宽高和排列方式有关
//        func collectionView(collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, referenceSizeForHeaderInSection section: Int) -> CGSize {
//            return CGSize(width: 10, height: 200)
//        }
//        func collectionView(collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, referenceSizeForFooterInSection section: Int) -> CGSize {
//            return CGSize(width: 100, height: 200)
//        }
}