collectionview使用

创建UICollectionViewFlowLayout 对象来设置相关的布局，包括itemSize，headerReferenceSize，sectionInset。设置对应的布局大小，相关的和顶部之间的间距等。

UICollectionView创建对应的view并且定义对应的大小，设置代理方法和数据源对象。

-(void)loadCollectionView
{
    UICollectionViewFlowLayout * collectionViewFlow = [[UICollectionViewFlowLayout alloc]init];
   UICollectionView *collectView = [[UICollectionView alloc]initWithFrame:CGRectMake(0, ScreenHeight, CGRectGetWidth(_homeScrollView.frame), 2000)collectionViewLayout:collectionViewFlow];
    
    collectView.dataSource = self;
    collectView.delegate = self;
    collectView.backgroundColor = [UIColor blueColor];
    [collectView registerClass:[CSHomeCollectionViewCell class] forCellWithReuseIdentifier:@"collectionCell"];
    collectionViewFlow.itemSize = CGSizeMake(93, 120);
    collectionViewFlow.sectionInset = UIEdgeInsetsMake(40, 0, 0, 0);
    collectionViewFlow.scrollDirection  = UICollectionViewScrollDirectionVertical;
    [_homeScrollView addSubview:collectView];
}
//datasource,delegate
-(NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section
{
    return 20;
}
-(UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
{
      CSHomeCollectionViewCell * cell = [collectionView dequeueReusableCellWithReuseIdentifier:@"collectionCell" forIndexPath:indexPath];
    cell.topImage.image = [UIImage imageNamed:@"cludy_bg"];
    return cell;
}

从而来实现对应的方法，其中自定义的cell类

-(instancetype)initWithFrame:(CGRect)frame
{
    self =[super initWithFrame:frame];
    if (self) {
        self.backgroundColor = [UIColor grayColor];
        self.topImage = [[UIImageView  alloc]initWithFrame:CGRectMake(5, 5, MYSIZE.width-10, MYSIZE.height*0.6)];
        [self addSubview:_topImage];
        
        self.designer = [[UILabel alloc]initWithFrame:CGRectMake(5, CGRectGetHeight(self.topImage.frame), CGRectGetWidth(self.frame), 20)];
    
        self.designer.text = @"hello";
        [self addSubview:_designer];
        
//        self.goodBtn = [UIButton alloc]initWithFrame:CGRectMake(0, <#CGFloat y#>, <#CGFloat width#>, <#CGFloat height#>)
        
    }
    return self;
}

当定义的时候，自动调用initwithframe函数来初始化