@protocol UICollectionViewDelegateFlowLayout <UICollectionViewDelegate>
@optional
- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath *)indexPath;
- (UIEdgeInsets)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout insetForSectionAtIndex:(NSInteger)section;
- (CGFloat)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout minimumLineSpacingForSectionAtIndex:(NSInteger)section;
- (CGFloat)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout minimumInteritemSpacingForSectionAtIndex:(NSInteger)section;
- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout referenceSizeForHeaderInSection:(NSInteger)section;
- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout referenceSizeForFooterInSection:(NSInteger)section;
@end
UICollectionViewDelegate：和UITableViewDelegate一样，这里就把它协议里面的的函数po出来了,通过重写里面的函数，我们可以实现cell的点击与拖动。
UIGestureRecognizerDelegate：由于我们还有一个拖动的功能，所以需要实现用户手势的协议。
好了，基础的概念讲了，现在我们就开始动手实现他吧！老样子直接看源码：
- (void)viewDidLoad {
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
//设置背景色
[self.view setBackgroundColor:[UIColor colorWithPatternImage:[UIImage imageNamed:@"back.jpg"]]];
//设置数据源
self.dataSource = [[NSMutableArray alloc] initWithObjects:
@"1.png",@"2.png",@"3.png", @"4.png", @"5.png", @"6.png", @"7.png", @"8.png", @"9.png", @"10.png", @"11.jpg", @"12.JPG",
@"13.JPG", @"14.jpg", @"15.JPG", @"16.png", @"17.png", @"18.png", @"19.png", @"20.png", nil nil];
//初始化布局
self.flow = [[UICollectionViewFlowLayout alloc] init];
self.collect = [[UICollectionView alloc] initWithFrame:CGRectZero collectionViewLayout:self.flow];
[self.collect setBackgroundColor:[UIColor clearColor]];
//注册cell 这一步必须要实现
[self.collect registerClass:[CustomCollectionCell class] forCellWithReuseIdentifier:@"CustomCell"];
self.collect.delegate = self;
self.collect.dataSource = self;
[self.collect setFrame:self.view.bounds];
//添加长按手势
self.longPressGestureRecognizer = [[UILongPressGestureRecognizer alloc] init];
[self.longPressGestureRecognizer addTarget:self action:@selector(handleLongPressRecognizer:)];
[self.collect addGestureRecognizer:self.longPressGestureRecognizer];
[self.view addSubview:self.collect];
}
