UICollectionView实现动画轮播

最近朋友接手一个项目，时间有点紧赶，便请我帮忙实现一个功能，首页滚动图，加动画效果。以前用ScrollView做过类似轮播图，但是用在这里可能会有点麻烦，就上网研究了下CollectionView，做出来后发现，其实很简单的，先看效果

下面上代码

//
//  ViewController.m
//  CollectionView轮播
//
//  Created by yuepengfei on 16/7/1.
//  Copyright © 2016年 weilili. All rights reserved.
//

#import "ViewController.h"
#import "CricleLayout.h"

@interface ViewController ()<UICollectionViewDelegate, UICollectionViewDataSource>

@property (nonatomic, strong) UICollectionView *myCollectionView;

@end

static NSString * const cellIdentifier =              @"cellIdentifier";
@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
    [self.view addSubview:self.myCollectionView];
}
#pragma mark - collectionView
- (UICollectionView *)myCollectionView
{
    if (!_myCollectionView) {

        CricleLayout *layout = [[CricleLayout alloc] init];
        _myCollectionView = [[UICollectionView alloc] initWithFrame:CGRectMake(0, 100, kScreen_width,