ios-collectionView单向滑动

swift 版本
import UIKit

class ViewController: UIViewController {
    
    var collectionView:UICollectionView?
    var currentIndexPath:IndexPath?
    override func viewDidLoad() {
        super.viewDidLoad()
        
        let cvLayout = UICollectionViewFlowLayout()
        cvLayout.itemSize = view.bounds.size
        cvLayout.scrollDirection = .horizontal
        
        collectionView = UICollectionView(frame: view.bounds, collectionViewLayout: cvLayout)
        collectionView?.delegate = self
        collectionView?.dataSource = self
//        collectionView?.isPagingEnabled = true
        collectionView?.isScrollEnabled = false
        
        collectionView?.register(UICollectionViewCell.self, forCellWithReuseIdentifier: "defaultCell")
        
        view.backgroundColor = #colorLiteral(red: 1, green: 1, blue: 1, alpha: 1)
        
        view.addSubview(collectionView!)
        let leftSwipe = UISwipeGestureRecognizer(target: self, action: #selector(leftAction(_:)))
        leftSwipe.direction = .left
        view.addGestureRecognizer(leftSwipe)
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
    }
    
    func leftAction(_ sender: UITapGestureRecognizer) {
        if currentIndexPath == nil {
            currentIndexPath = IndexPath(row: 0, section: 0)
        }
        if (currentIndexPath?.row)! + 1 >= (collectionView?.numberOfItems(inSection: currentIndexPath!.section))! {// 控制滑到最右边
            return
        }
        currentIndexPath = IndexPath(row: (currentIndexPath?.row)! + 1, section: (currentIndexPath?.section)!)
        collectionView?.scrollToItem(at: currentIndexPath!, at: .right, animated: true)
    }
    
}

extension ViewController: UICollectionViewDelegateFlowLayout,UICollectionViewDataSource {
    
    func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        return 5
    }
    
    func numberOfSections(in collectionView: UICollectionView) -> Int {
        return 1
    }
    
    func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "defaultCell", for: indexPath)
        let red = CGFloat(arc4random() % 256) / 255.0
        let green = CGFloat(arc4random() % 256) / 255.0
        let blue = CGFloat(arc4random() % 256) / 255.0
//        print("\(red) - \(green) - \(blue)")
        cell.backgroundColor = UIColor(red: CGFloat(red), green: CGFloat(green), blue: CGFloat(blue), alpha: 1.0)
        return cell
    }
    
}

OC版本
#import "ViewController.h"

@interface ViewController () <UICollectionViewDataSource,UICollectionViewDelegateFlowLayout>

@property (nonatomic,strong) UICollectionView *collectionView;

@property (nonatomic,strong) NSIndexPath *currentIndexPath;

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    self.view.backgroundColor = [UIColor whiteColor];
    
    UISwipeGestureRecognizer *leftSwipe = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(leftAction:)];
    leftSwipe.direction = UISwipeGestureRecognizerDirectionLeft;
    [self.view addGestureRecognizer:leftSwipe];
}

- (void)leftAction:(UISwipeGestureRecognizer *)sender {
    if (self.currentIndexPath == nil) {
        self.currentIndexPath = [NSIndexPath indexPathForItem:0 inSection:0 ];
    }

    if (self.currentIndexPath.item + 1 >= [self.collectionView numberOfItemsInSection:self.currentIndexPath.section]) { // 控制滑到最右边
        return;
    }
    self.currentIndexPath = [NSIndexPath indexPathForItem:self.currentIndexPath.row + 1 inSection:self.currentIndexPath.section];
    [self.collectionView scrollToItemAtIndexPath:self.currentIndexPath atScrollPosition:UICollectionViewScrollPositionRight animated:YES];
}


#pragma mark - collectionView
- (UICollectionView *)collectionView
{
    if (!_collectionView) {
        
        UICollectionViewFlowLayout *layout = [[UICollectionViewFlowLayout alloc] init];
        layout.itemSize = self.view.bounds.size;
        layout.scrollDirection = UICollectionViewScrollDirectionHorizontal;
        
        _collectionView = [[UICollectionView alloc] initWithFrame:self.view.bounds collectionViewLayout:layout];
        
        _collectionView.dataSource = self;
        _collectionView.delegate = self;
        _collectionView.scrollEnabled = NO;
//        [_collectionView registerNib:[UINib nibWithNibName:@"" bundle:nil] forCellWithReuseIdentifier:@""];
        [_collectionView registerClass:UICollectionViewCell.self forCellWithReuseIdentifier:@"cell"];
        _collectionView.backgroundColor = [UIColor whiteColor];
        
        _collectionView.showsVerticalScrollIndicator = NO;
        _collectionView.showsHorizontalScrollIndicator = NO;
        
        [self.view addSubview:_collectionView];
    }
    return _collectionView;
}

#pragma mark  collectionViewDataSource -  UICollectionViewDelegateFlowLayout

/* 个数 **/
- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section
{
    return 5;
}

/* 选中 **/
- (void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath
{
    
}

/* cell设置 **/
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
{
    UICollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:@"cell" forIndexPath:indexPath];
    
    cell.backgroundColor = [UIColor colorWithRed:(arc4random() % 256) /255.0 green:(arc4random() % 256) /255.0 blue:(arc4random() % 256) /255.0 alpha:1];
    
    return cell;
}