UICollectionView的初始化

gistfile1.m

-(void)initUICollectionView{
    //初始化布局方式，这里采用垂直布局。
    UICollectionViewFlowLayout *flowLayout=[[UICollectionViewFlowLayout alloc] init];
    [flowLayout setScrollDirection:UICollectionViewScrollDirectionVertical];
    
    UICollectionView *collectionView=[[UICollectionView alloc] initWithFrame:CGRectZero collectionViewLayout:flowLayout];
    [self.view addSubview:collectionView];
}