UICollectionView使用以及与UITableView的区别

　　在开始前我们在这先附一段最简单的代码

- (void)viewDidLoad
{
    [super viewDidLoad];
    
    UICollectionViewFlowLayout *layout = [[UICollectionViewFlowLayout alloc] init];
    
    UICollectionView *colView = [[UICollectionView alloc] initWithFrame:self.view.bounds collectionViewLayout:layout];
    colView.backgroundColor = [UIColor grayColor];
    [colView registerClass:[UICollectionViewCell class] forCellWithReuseIdentifier:@"myCell"];
    colView.delegate = self;
    colView.dataSource = self;
    
    [self.view addSubview:colView];

}

- (NSArray *)loadData
{
    NSArray *arr = [NSArray arrayWithObjects:@"cell", @"cell2", @"cell3", @"cell4", @"cell5", @"cell6", @"cell7",nil];
    return arr;
}

#pragma mark - UICollectionViewDataSource

- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section
{
    return [[self loadData] count];
}

- (NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView
{
    return 1;
}

- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
{
    static NSString *cellID = @"myCell";
    UICollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:cellID forIndexPath:indexPath];
    cell.backgroundColor = [UIColor redColor];
    return cell;
}

代码