iOS UICollectionView 使用详解

   // 代码创建  所属controller要遵循三个协议：UICollectionViewDataSource,UICollectionViewDelegate,UICollectionViewDelegateFlowLayout     UICollectionViewFlowLayout *flowLayout = [[UICollectionViewFlowLayout alloc]init];      [flowLayout setItemSize:CGSizeMake(70, 100)];//设置cell的尺寸      [flowLayout setScrollDirection:UICollectionViewScrollDirectionVertical];//设置其布局方向      flowLayout.sectionInset = UIEdgeInsetsMake(5, 5, 5, 5);//设置其边界  //其布局很有意思，当你的cell设置大小后，一行多少个cell，由cell的宽度决定            _collectionView = [[UICollectionView alloc]initWithFrame:CGRectMake(0, 0, 320, self.view.frame.size.height)collectionViewLayout:flowLayout];      _collectionView.dataSource = self;      _collectionView.delegate = self;      _collectionView.backgroundColor = [UIColor clearColor];      [_collectionView registerClass:[BMCollectionCell class] forCellWithReuseIdentifier:CELL_ID];      [self.view addSubview:_collectionView];      [_collectionView release];  //collectionView的代理方法  #pragma mark - collectionView dataSource Or delegate  -(NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section  {      return 32;  }  -(NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView  {      return 1;  }  -(UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath  {      BMCollectionCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:CELL_IDforIndexPath:indexPath];      return cell;  }  -(void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath  {      NSLog(@"%s",__FUNCTION__);     }
 //定义展示的UICollectionViewCell的个数

 -(NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section
 {
     return 30;
 }

 //定义展示的Section的个数
 -(NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView
 {
     return 1;
 }

 //每个UICollectionView展示的内容
 -(UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
 {
     static NSString * CellIdentifier = @"GradientCell";
     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];
     return cell;
 }

 #pragma mark --UICollectionViewDelegateFlowLayout

 //定义每个UICollectionView 的大小
 - (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath *)indexPath
 {
     return CGSizeMake(96, 100);
 }

 //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];
     cell.backgroundColor = [UIColor whiteColor];
 }

 //返回这个UICollectionView是否可以被选择
 -(BOOL)collectionView:(UICollectionView *)collectionView shouldSelectItemAtIndexPath:(NSIndexPath *)indexPath
 {
     return YES;
 }

 

 

 

下面通过一个例子具体介绍下。（例子来自网络。但是是通过第三方获得的，无法取得链接。还望见谅。）

 

iOS CollectionView的出现是一大福利，再也不用用TableView来定义复杂的多栏表格了，用法与Table类似，只是Cell必须自己添加，无默认模式

由于CollectionView没有默认的Cell布局，所以一般还是自定义方便又快捷

一、自定义Cell

1、新建类CollectionCell继承自UICollectionViewCell

2、新建Xib，命名为CollectionCell.xib

a.选中CollectionCell.xib删掉默认的View，从控件中拖一个Collection View Cell（图3）到画布中，设置大小为95*116；

 

b.选中刚刚添加的Cell，更改类名为CollectionCell，如图4

c.在CollectionCell.xib的CollectionCell中添加一个ImageView和一个Label（图5）

d.创建映射, 图6，图7

e.选中CollectionCell.m , 重写init方法 

 - (id)initWithFrame:(CGRect)frame
 {
     self = [super initWithFrame:frame];
     if (self)
     {
         // 初始化时加载collectionCell.xib文件
         NSArray *arrayOfViews = [[NSBundle mainBundle] loadNibNamed:@"CollectionCell" owner:self options:nil];

         // 如果路径不存在，return nil
         if (arrayOfViews.count < 1)
         {
             return nil;
         }
         // 如果xib中view不属于UICollectionViewCell类，return nil
         if (![[arrayOfViews objectAtIndex:0] isKindOfClass:[UICollectionViewCell class]])
         {
             return nil;
         }
         // 加载nib
         self = [arrayOfViews objectAtIndex:0];
     }
     return self;
 }

f.选中CollectionCell.xib 修改其identifier为CollectionCell。

二、定义UICollectionView；

1、拖动一个Collection View到指定ViewController的View上

2、连线dataSource和delegate，并创建映射，命名为CollectionView

3、选中CollectionView的标尺，将Cell Size的Width和Height改成与自定义的Cell一样的95*116,图8

    

4、选中CollectionView的属性,可以修改其属性，比如是垂直滑动，还是水平滑动，选择Vertical或Horizontal

5、选中CollectionViewCell，修改Class，继承自CollectionCell

5、在ViewDidLoad方法中声明Cell的类，在ViewDidLoad方法中添加，此句不声明，将无法加载，程序崩溃

其中,CollectionCell是这个Cell的标识（之前几步已经定义过了。 ） 

 [self.collectionView registerClass:[CollectionCell class] forCellWithReuseIdentifier:@"CollectionCell"];

6、在ViewController.h中声明代理 

 @interface ViewController : UIViewController<UICollectionViewDataSource,UICollectionViewDelegate>

 

7、在.m文件中实现代理方法 

 //每个section的item个数
 -(NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section
 {
     return 12;
 }

 -(UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
 {

     CollectionCell *cell = (CollectionCell *)[collectionView dequeueReusableCellWithReuseIdentifier:@"CollectionCell" forIndexPath:indexPath];

     //图片名称
     NSString *imageToLoad = [NSString stringWithFormat:@"%d.png", indexPath.row];
     //加载图片
     cell.imageView.image = [UIImage imageNamed:imageToLoad];
     //设置label文字
     cell.label.text = [NSString stringWithFormat:@"{%ld,%ld}",(long)indexPath.row,(long)indexPath.section];

     return cell;
 }

 

8 。效果如图10

点击某项后跳转事件与UITableView类似，实现代理方法 

-(void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath 例子2   #import "RootViewController.h" #import "CustomCollectionViewCell.h" @interface RootViewController ()<UICollectionViewDelegate,UICollectionViewDataSource,UICollectionViewDelegateFlowLayout> @property (nonatomic,retain)NSDictionary *itemDic; // 承载一个item上面显示的图片和文字 @property (nonatomic,retain)NSMutableArray *allDataArray; // 成方所有的item上显示的内容，其实就是盛放小字典 @end @implementation RootViewController - (NSMutableArray *)allDataArray{ if (!_allDataArray) { _allDataArray = [[NSMutableArray alloc]init]; }return _allDataArray; } - (void)viewDidLoad { [super viewDidLoad]; for (int i = 1; i < 20; i++) { NSDictionary *itemDic = [[NSDictionary alloc] initWithObjectsAndKeys: [NSString stringWithFormat:@"%d.jpg",i],@"imageName", [NSString stringWithFormat:@"我是第%d个妹子",i] ,@"textLable", nil]; [self.allDataArray addObject:itemDic]; } self.navigationItem.title = @"github"; // 由于初始化集合视图需要布局对象，所以我们才需要初始化布局对象，并且设置它的某些属性 // 这个是系统提供的布局类，可以布局一些比较规则的布局。 UICollectionViewFlowLayout *flowLayout = [[UICollectionViewFlowLayout alloc] init]; // 设置每个item的大小， flowLayout.itemSize = CGSizeMake(120, 160); // flowLayout.itemSize = CGSizeMake(CGRectGetWidth(self.view.frame), CGRectGetHeight(self.view.frame)); // 设置列的最小间距 flowLayout.minimumInteritemSpacing = 10; // 设置最小行间距 flowLayout.minimumLineSpacing = 15; // 设置布局的内边距 flowLayout.sectionInset = UIEdgeInsetsMake(15, 15, 15, 15); // 滚动方向 flowLayout.scrollDirection = UICollectionViewScrollDirectionVertical; // flowLayout.scrollDirection = UICollectionViewScrollDirectionHorizontal; UICollectionView *collectionView = [[UICollectionView alloc] initWithFrame:self.view.bounds collectionViewLayout:flowLayout]; // 如果未设置背景颜色是黑色设置背景颜色 collectionView.backgroundColor = [UIColor whiteColor]; // 设置代理 collectionView.delegate = self; collectionView.dataSource = self; // [collectionView registerClass:[UICollectionViewCell class] forCellWithReuseIdentifier:@"CELL"]; [collectionView registerClass:[CustomCollectionViewCell class] forCellWithReuseIdentifier:@"CELL"]; [self.view addSubview:collectionView]; } // 返回分区数 - (NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView{ return 1; } // 每个分区多少个item - (NSInteger )collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section{ return _allDataArray.count; } - (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath{ // UICollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:@"CELL" forIndexPath:indexPath]; CustomCollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:@"CELL" forIndexPath:indexPath]; // 取出每个item所需要的数据 NSDictionary *dic = [_allDataArray objectAtIndex:indexPath.item]; // 取出图片名称 NSString *imageString = [dic objectForKey:@"imageName"]; cell.imageView.image = [UIImage imageNamed:imageString]; // 取出文字 NSString *textString = [dic objectForKey:@"textLable"]; cell.titleLabel.text = textString; cell.backgroundColor = [UIColor colorWithRed:arc4random()%256/256.0 green:arc4random()%256/256.0 blue:arc4random()%256/256.0 alpha:1]; return cell; } // 点击图片的方法 - (void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath{ NSLog(@"我点击了%ld图片！！！",indexPath.item + 1); } - (void)didReceiveMemoryWarning { [super didReceiveMemoryWarning]; // Dispose of any resources that can be recreated. } /* #pragma mark - Navigation // In a storyboard-based application, you will often want to do a little preparation before navigation - (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender { // Get the new view controller using [segue destinationViewController]. // Pass the selected object to the new view controller. } */ @end CustomCollectionViewCell.h #import <UIKit/UIKit.h> @interface CustomCollectionViewCell : UICollectionViewCell @property (nonatomic,retain)UIImageView *imageView; // 显示图片 @property (nonatomic,retain)UILabel *titleLabel; // 显示文字 @end CustomCollectionViewCell.m #import "CustomCollectionViewCell.h" @implementation CustomCollectionViewCell - (UIImageView *)imageView{ if (!_imageView) { _imageView = [[UIImageView alloc] initWithFrame:self.viewForFirstBaselineLayout.bounds]; [self.contentView addSubview:_imageView]; }return _imageView; } - (UILabel *)titleLabel{ if (!_titleLabel) { _titleLabel = [[UILabel alloc] initWithFrame:CGRectMake(0, CGRectGetHeight(self.bounds) - 30, CGRectGetWidth(self.bounds), 30)]; [self.contentView addSubview:_titleLabel]; }return _titleLabel; } @end 三、成品展