UICollectionView 的使用详解

#import <UIKit/UIKit.h>@interface ViewController : UIViewController<UICollectionViewDataSource,UICollectionViewDelegateFlowLayout>{}@property (strong, nonatomic)UICollectionView *collectionView;@end

ViewController.m

#import "ViewController.h"@interface ViewController ()@end@implementation ViewController- (void)viewDidLoad{  [super viewDidLoad];    //确定是水平滚动，还是垂直滚动  UICollectionViewFlowLayout *flowLayout=[[UICollectionViewFlowLayout alloc] init];  [flowLayout setScrollDirection:UICollectionViewScrollDirectionVertical];    self.collectionView=[[UICollectionView alloc] initWithFrame:CGRectMake(0, 64, 320, 200) collectionViewLayout:flowLayout];  self.collectionView.dataSource=self;  self.collectionView.delegate=self;  [self.collectionView setBackgroundColor:[UIColor clearColor]];    //注册Cell，必须要有  [self.collectionView registerClass:[UICollectionViewCell class] forCellWithReuseIdentifier:@"UICollectionViewCell"];    [self.view addSubview:self.collectionView];}#pragma mark -- UICollectionViewDataSource//定义展示的UICollectionViewCell的个数-(NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section{  return 10;}//定义展示的Section的个数-(NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView{  return 2;}//每个UICollectionView展示的内容-(UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath{  static NSString * CellIdentifier = @"UICollectionViewCell";  UICollectionViewCell * cell = [collectionView dequeueReusableCellWithReuseIdentifier:CellIdentifier forIndexPath:indexPath];    cell.backgroundColor = [UIColor colorWithRed:((10 * indexPath.row) / 255.0) green:((20 * indexPath.row)/255.0) blue:((30 * indexPath.row)/255.0) alpha:1.0f];  UILabel *label = [[UILabel alloc] initWithFrame:CGRectMake(0, 0, 20, 20)];  label.textColor = [UIColor redColor];  label.text = [NSString stringWithFormat:@"%d",indexPath.row];   for (id subView in cell.contentView.subviews) {    [subView removeFromSuperview];  }  [cell.contentView addSubview:label];  return cell;}#pragma mark --UICollectionViewDelegateFlowLayout//定义每个Item 的大小- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath *)indexPath{  return CGSizeMake(60, 60);}//定义每个UICollectionView 的 margin-(UIEdgeInsets)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout insetForSectionAtIndex:(NSInteger)section{  return UIEdgeInsetsMake(5, 5, 5, 5);}#pragma mark --UICollectionViewDelegate//UICollectionView被选中时调用的方法-(void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath{  UICollectionViewCell * cell = (UICollectionViewCell *)[collectionView cellForItemAtIndexPath:indexPath];  //临时改变个颜色，看好，只是临时改变的。如果要永久改变，可以先改数据源，然后在cellForItemAtIndexPath中控制。（和UITableView差不多吧！O(∩_∩)O~）  cell.backgroundColor = [UIColor greenColor];  NSLog(@"item======%d",indexPath.item);  NSLog(@"row=======%d",indexPath.row);  NSLog(@"section===%d",indexPath.section);}//返回这个UICollectionView是否可以被选择-(BOOL)collectionView:(UICollectionView *)collectionView shouldSelectItemAtIndexPath:(NSIndexPath *)indexPath{  return YES;}@end