UICollectionView的简单使用

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项目应用：

#import "HomeGroupOrderCell.h"

#import "HomeGroupOrderCollectionViewCell.h"

@interface HomeGroupOrderCell ()<UICollectionViewDelegate,UICollectionViewDataSource>

@property (weak, nonatomic) IBOutlet UICollectionView *collectionView;

@end

@implementation HomeGroupOrderCell

- (void)awakeFromNib {

[super awakeFromNib];

UICollectionViewFlowLayout *layout = [UICollectionViewFlowLayout new];

//移动方向(纵向移动)

// layout.scrollDirection = UICollectionViewScrollDirectionVertical;

//同一行每个collectionCell之间的间距

// layout.minimumLineSpacing = 5;

//同一个Section下，每行之间的间距

// layout.minimumInteritemSpacing = 5;

[self.collectionView setCollectionViewLayout:layout];

self.collectionView.scrollEnabled = NO;

self.collectionView.scrollsToTop = NO;

//是否显示移动条

self.collectionView.showsVerticalScrollIndicator = NO;

self.collectionView.showsHorizontalScrollIndicator = NO;

// [self.collectionView setContentSize:CGSizeMake(self.dataArray.count*((ScreenWidth-40)/3+5), 0)];

// self.collectionView.backgroundColor = COLOR_HEX(@"#f3f3f3");

self.collectionView.delegate=self;

self.collectionView.dataSource=self;

//注册CollectionViewCell

[self.collectionView registerNib:[UINibnibWithNibName:@"HomeGroupOrderCollectionViewCell" bundle:[NSBundlemainBundle]] forCellWithReuseIdentifier:@"groupCell"];

}

#pragma mark --- UICollectionViewDataSource

//分区数

- (NSInteger)numberOfSectionsInCollectionView:(UICollectionView*)collectionView{

if (self.dataArray.count>0) {

return (self.dataArray.count+1)/2;

}else{

return 0;

}

//设置每个分区的item个数

-(NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section

{

if (self.dataArray.count%2 == 0) {

return 2;

}else{

if (section == (self.dataArray.count+1)/2) {

return 1;

}else{

return 2;

}

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

{

HomeGroupOrderCollectionViewCell* cell=[collectionView dequeueReusableCellWithReuseIdentifier:@"groupCell" forIndexPath:indexPath];

// [cell setContentWithProductInfo:self.dataArray[indexPath.row] IndexPath:indexPath];

// NSString *goods_id = self.dataArray[indexPath.row][@"goods_id"];

// cell.orderNowBlock = ^(NSIndexPath *index) {

// !self.orderNowBlock? :self.orderNowBlock(index,goods_id);

// };

return cell;

}

//item的size

-(CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath *)indexPath{

return CGSizeMake((ScreenWidth-5)/2, (ScreenWidth-5)/2+9+37+15+25+17);

}

//用于调节每个section的上左下右的距离

-(UIEdgeInsets)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout insetForSectionAtIndex:(NSInteger)section

{

return UIEdgeInsetsMake(5, 0, 0, 0);//分别为上、左、下、右

}

////同一个section中不同的行之间的行间距

//- (CGFloat)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout minimumLineSpacingForSectionAtIndex:(NSInteger)section

//{

// return 5;

//}

//每个item之间的间距

- (CGFloat)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout minimumInteritemSpacingForSectionAtIndex:(NSInteger)section

{

return 0;

}

-(void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath{

// NSString *goods_id = self.dataArray[indexPath.row][@"goods_id"];

// !self.goToGoodsDetailBlock? :self.goToGoodsDetailBlock(goods_id);

}

UICollectionView的应用：

－. 布局
UICollectionViewFlowLayout流水布局
通过UICollectionViewFlowLayout对象进行布局( 如果布局的尺寸是固定的，例如：item的尺寸大小都是固定，可以使用全局属性，即设置下文中layout ) UICollectionViewFlowLayout *layout = [[UICollectionViewFlowLayout alloc] init]; // 1.设置列间距 layout.minimumInteritemSpacing = 1; // 2.设置行间距 layout.minimumLineSpacing = 1; // 3.设置每个item的大小 layout.itemSize = CGSizeMake(50, 50); // 4.设置Item的估计大小,用于动态设置item的大小，结合自动布局（self-sizing-cell） layout.estimatedItemSize = CGSizeMake(320, 60); // 5.设置布局方向 layout.scrollDirection = UICollectionViewScrollDirectionHorizontal; // 6.设置头视图尺寸大小 layout.headerReferenceSize = CGSizeMake(50, 50); // 7.设置尾视图尺寸大小 layout.footerReferenceSize = CGSizeMake(50, 50); // 8.设置分区(组)的EdgeInset（四边距） layout.sectionInset = UIEdgeInsetsMake(10, 20, 30, 40); // 9.10.设置分区的头视图和尾视图是否始终固定在屏幕上边和下边 layout.sectionFootersPinToVisibleBounds = YES; layout.sectionHeadersPinToVisibleBounds = YES;
通过遵守UICollectionViewDelegateFlowLayout实现代理方法来布局（非固定情况则需要通过数据源方法）
- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath *)indexPath;- (UIEdgeInsets)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout insetForSectionAtIndex:(NSInteger)section;- (CGFloat)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout minimumLineSpacingForSectionAtIndex:(NSInteger)section;- (CGFloat)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout minimumInteritemSpacingForSectionAtIndex:(NSInteger)section;- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout referenceSizeForHeaderInSection:(NSInteger)section;- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout referenceSizeForFooterInSection:(NSInteger)section;
二. 数据源方法
//设置分区数（必须实现）- (NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView {    return 1;}//设置每个分区的item个数- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section{     return 5;  }//设置返回每个item的属性必须实现）- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath{    UICollectionViewCell *cell = [self.collection dequeueReusableCellWithReuseIdentifier:ID forIndexPath:indexPath];    return cell;}//对头视图或者尾视图进行设置- (UICollectionReusableView *)collectionView:(UICollectionView *)collectionView viewForSupplementaryElementOfKind:(NSString *)kind atIndexPath:(NSIndexPath *)indexPath {    NSString *identifier;    if ([kind isEqualToString:UICollectionElementKindSectionHeader]) {        identifier = @"headerView";    } else {        identifier = @"footerView";    }    UICollectionReusableView *view = [collectionView dequeueReusableSupplementaryViewOfKind:kind withReuseIdentifier:identifier forIndexPath:indexPath];    UILabel *label = [[UILabel alloc] initWithFrame:CGRectMake(0, 10, 120, 30)];    [view addSubview:label];    if (indexPath.section == 0) {        label.text = @"section1";    }else {        label.text = @"section2";    }    if ([kind isEqualToString:UICollectionElementKindSectionHeader]) {        view.backgroundColor = [UIColor redColor];    } else {        view.backgroundColor = [UIColor purpleColor];    }    return view;}//是否允许移动Item- (BOOL)collectionView:(UICollectionView *)collectionView canMoveItemAtIndexPath:(NSIndexPath *)indexPath NS_AVAILABLE_IOS(9_0){    return YES;}//移动Item时触发的方法- (void)collectionView:(UICollectionView *)collectionView moveItemAtIndexPath:(NSIndexPath *)sourceIndexPath toIndexPath:(NSIndexPath*)destinationIndexPath NS_AVAILABLE_IOS(9_0); {}
三. 常用到的代理方法
//是否允许某个Item的高亮，返回NO，则不能进入高亮状态- (BOOL)collectionView:(UICollectionView *)collectionView shouldHighlightItemAtIndexPath:(NSIndexPath *)indexPath; {    return YES;}//当item高亮时触发的方法- (void)collectionView:(UICollectionView *)collectionView didHighlightItemAtIndexPath:(NSIndexPath *)indexPath; {}//结束高亮状态时触发的方法- (void)collectionView:(UICollectionView *)collectionView didUnhighlightItemAtIndexPath:(NSIndexPath *)indexPath; {}//是否可以选中某个Item，返回NO，则不能选中- (BOOL)collectionView:(UICollectionView *)collectionView shouldSelectItemAtIndexPath:(NSIndexPath *)indexPath; {    return YES;}//是否可以取消选中某个Item- (BOOL)collectionView:(UICollectionView *)collectionView shouldDeselectItemAtIndexPath:(NSIndexPath *)indexPath; {    return YES;}//已经选中某个item时触发的方法- (void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath; {}//取消选中某个Item时触发的方法- (void)collectionView:(UICollectionView *)collectionView didDeselectItemAtIndexPath:(NSIndexPath *)indexPath; {}//将要加载某个Item时调用的方法- (void)collectionView:(UICollectionView *)collectionView willDisplayCell:(UICollectionViewCell *)cell forItemAtIndexPath:(NSIndexPath *)indexPath NS_AVAILABLE_IOS(8_0); {}//将要加载头尾视图时调用的方法- (void)collectionView:(UICollectionView *)collectionView willDisplaySupplementaryView:(UICollectionReusableView *)view forElementKind:(NSString *)elementKind atIndexPath:(NSIndexPath *)indexPath NS_AVAILABLE_IOS(8_0); {}//已经展示某个Item时触发的方法- (void)collectionView:(UICollectionView *)collectionView didEndDisplayingCell:(UICollectionViewCell *)cell forItemAtIndexPath:(NSIndexPath *)indexPath; {}//已经展示某个头尾视图时触发的方法- (void)collectionView:(UICollectionView *)collectionView didEndDisplayingSupplementaryView:(UICollectionReusableView *)view forElementOfKind:(NSString *)elementKind atIndexPath:(NSIndexPath *)indexPath; {}//这个方法设置是否展示长按菜单- (BOOL)collectionView:(UICollectionView *)collectionView shouldShowMenuForItemAtIndexPath:(NSIndexPath *)indexPath; {    return YES;}//这个方法用于设置要展示的菜单选项- (BOOL)collectionView:(UICollectionView *)collectionView canPerformAction:(SEL)action forItemAtIndexPath:(NSIndexPath *)indexPath withSender:(nullable id)sender; {    return YES;}//这个方法用于实现点击菜单按钮后的触发方法,通过测试，只有copy，cut和paste三个方法可以使用- (void)collectionView:(UICollectionView *)collectionView performAction:(SEL)action forItemAtIndexPath:(NSIndexPath *)indexPath withSender:(nullable id)sender; {    //通过下面的方式可以将点击按钮的方法名打印出来：    NSLog(@"%@",NSStringFromSelector(action));}//collectionView进行重新布局时调用的方法//- (nonnull UICollectionViewTransitionLayout *)collectionView:(UICollectionView *)collectionView transitionLayoutForOldLayout:(UICollectionViewLayout *)fromLayout newLayout:(UICollectionViewLayout *)toLayout; {////}
四. collectionView的属性和相关方法
//通过一个布局策略初识化CollectionView    - (instancetype)initWithFrame:(CGRect)frame collectionViewLayout:(UICollectionViewLayout *)layout;    //获取和设置collection的layout    @property (nonatomic, strong) UICollectionViewLayout *collectionViewLayout;    //数据源和代理    @property (nonatomic, weak, nullable) id <UICollectionViewDelegate> delegate;    @property (nonatomic, weak, nullable) id <UICollectionViewDataSource> dataSource;    //从一个class或者xib文件进行cell(item)的注册    - (void)registerClass:(nullable Class)cellClass forCellWithReuseIdentifier:(NSString *)identifier;    - (void)registerNib:(nullable UINib *)nib forCellWithReuseIdentifier:(NSString *)identifier;    //下面两个方法与上面相似，这里注册的是头视图或者尾视图的类    //其中第二个参数是设置 头视图或者尾视图 系统为我们定义好了这两个字符串    //UIKIT_EXTERN NSString *const UICollectionElementKindSectionHeader NS_AVAILABLE_IOS(6_0);    //UIKIT_EXTERN NSString *const UICollectionElementKindSectionFooter NS_AVAILABLE_IOS(6_0);    - (void)registerClass:(nullable Class)viewClass forSupplementaryViewOfKind:(NSString *)elementKind withReuseIdentifier:(NSString *)identifier;    - (void)registerNib:(nullable UINib *)nib forSupplementaryViewOfKind:(NSString *)kind withReuseIdentifier:(NSString *)identifier;    //这两个方法是从复用池中取出cell或者头尾视图    - (__kindof UICollectionViewCell *)dequeueReusableCellWithReuseIdentifier:(NSString *)identifier forIndexPath:(NSIndexPath *)indexPath;    - (__kindof UICollectionReusableView *)dequeueReusableSupplementaryViewOfKind:(NSString *)elementKind withReuseIdentifier:(NSString *)identifier forIndexPath:(NSIndexPath *)indexPath;    //设置是否允许选中 默认yes    @property (nonatomic) BOOL allowsSelection;    //设置是否允许多选 默认no    @property (nonatomic) BOOL allowsMultipleSelection;    //获取所有选中的item的位置信息    - (nullable NSArray<NSIndexPath *> *)indexPathsForSelectedItems;    //设置选中某一item，并使视图滑动到相应位置，scrollPosition是滑动位置的相关参数，如下：    /*     typedef NS_OPTIONS(NSUInteger, UICollectionViewScrollPosition) {     //无     UICollectionViewScrollPositionNone                 = 0,     //垂直布局时使用的 对应上中下     UICollectionViewScrollPositionTop                  = 1 << 0,     UICollectionViewScrollPositionCenteredVertically   = 1 << 1,     UICollectionViewScrollPositionBottom               = 1 << 2,     //水平布局时使用的  对应左中右     UICollectionViewScrollPositionLeft                 = 1 << 3,     UICollectionViewScrollPositionCenteredHorizontally = 1 << 4,     UICollectionViewScrollPositionRight                = 1 << 5     };     */    - (void)selectItemAtIndexPath:(nullable NSIndexPath *)indexPath animated:(BOOL)animated scrollPosition:(UICollectionViewScrollPosition)scrollPosition;    //将某一item取消选中    - (void)deselectItemAtIndexPath:(NSIndexPath *)indexPath animated:(BOOL)animated;    //重新加载数据    - (void)reloadData;    //下面这两个方法，可以重新设置collection的布局，后面的方法多了一个布局完成后的回调，iOS7后可以用    //使用这两个方法可以产生非常炫酷的动画效果    - (void)setCollectionViewLayout:(UICollectionViewLayout *)layout animated:(BOOL)animated;    - (void)setCollectionViewLayout:(UICollectionViewLayout *)layout animated:(BOOL)animated completion:(void (^ __nullable)(BOOL finished))completion NS_AVAILABLE_IOS(7_0);    //下面这些方法更加强大，我们可以对布局更改后的动画进行设置    //这个方法传入一个布局策略layout，系统会开始进行布局渲染，返回一个UICollectionViewTransitionLayout对象    //这个UICollectionViewTransitionLayout对象管理动画的相关属性，我们可以进行设置    - (UICollectionViewTransitionLayout *)startInteractiveTransitionToCollectionViewLayout:(UICollectionViewLayout *)layout completion:(nullable UICollectionViewLayoutInteractiveTransitionCompletion)completion NS_AVAILABLE_IOS(7_0);    //准备好动画设置后，我们需要调用下面的方法进行布局动画的展示，之后会调用上面方法的block回调    - (void)finishInteractiveTransition NS_AVAILABLE_IOS(7_0);    //调用这个方法取消上面的布局动画设置，之后也会进行上面方法的block回调    - (void)cancelInteractiveTransition NS_AVAILABLE_IOS(7_0);    //获取分区数    - (NSInteger)numberOfSections;    //获取某一分区的item数    - (NSInteger)numberOfItemsInSection:(NSInteger)section;    //下面两个方法获取item或者头尾视图的layout属性，这个UICollectionViewLayoutAttributes对象    //存放着布局的相关数据，可以用来做完全自定义布局，后面博客会介绍    - (nullable UICollectionViewLayoutAttributes *)layoutAttributesForItemAtIndexPath:(NSIndexPath *)indexPath;    - (nullable UICollectionViewLayoutAttributes *)layoutAttributesForSupplementaryElementOfKind:(NSString *)kind atIndexPath:(NSIndexPath *)indexPath;    //获取某一点所在的indexpath位置    - (nullable NSIndexPath *)indexPathForItemAtPoint:(CGPoint)point;    //获取某个cell所在的indexPath    - (nullable NSIndexPath *)indexPathForCell:(UICollectionViewCell *)cell;    //根据indexPath获取cell    - (nullable UICollectionViewCell *)cellForItemAtIndexPath:(NSIndexPath *)indexPath;    //获取所有可见cell的数组    - (NSArray<__kindof UICollectionViewCell *> *)visibleCells;    //获取所有可见cell的位置数组    - (NSArray<NSIndexPath *> *)indexPathsForVisibleItems;    //下面三个方法是iOS9中新添加的方法，用于获取头尾视图    - (UICollectionReusableView *)supplementaryViewForElementKind:(NSString *)elementKind atIndexPath:(NSIndexPath *)indexPath NS_AVAILABLE_IOS(9_0);    - (NSArray<UICollectionReusableView *> *)visibleSupplementaryViewsOfKind:(NSString *)elementKind NS_AVAILABLE_IOS(9_0);    - (NSArray<NSIndexPath *> *)indexPathsForVisibleSupplementaryElementsOfKind:(NSString *)elementKind NS_AVAILABLE_IOS(9_0);    //使视图滑动到某一位置，可以带动画效果    - (void)scrollToItemAtIndexPath:(NSIndexPath *)indexPath atScrollPosition:(UICollectionViewScrollPosition)scrollPosition animated:(BOOL)animated;    //下面这些方法用于动态添加，删除，移动某些分区获取items    - (void)insertSections:(NSIndexSet *)sections;    - (void)deleteSections:(NSIndexSet *)sections;    - (void)reloadSections:(NSIndexSet *)sections;    - (void)moveSection:(NSInteger)section toSection:(NSInteger)newSection;    - (void)insertItemsAtIndexPaths:(NSArray<NSIndexPath *> *)indexPaths;    - (void)deleteItemsAtIndexPaths:(NSArray<NSIndexPath *> *)indexPaths;    - (void)reloadItemsAtIndexPaths:(NSArray<NSIndexPath *> *)indexPaths;    - (void)moveItemAtIndexPath:(NSIndexPath *)indexPath toIndexPath:(NSIndexPath *)newIndexPath;
五，自定义布局
UICollectionViewDelegateFlowLayout可以继承这个自定义自定义UICollectionViewLayout(抽象类):- (void)prepareLayout{    [super prepareLayout];}-(UICollectionViewLayoutAttributes *)layoutAttributesForItemAtIndexPath:(NSIndexPath *)indexPath{    NSMutableDictionary *dict;    dict[@"0"] = @1;    dict[@"1"] = @2;    UICollectionViewLayoutAttributes *attrs = [UICollectionViewLayoutAttributes layoutAttributesForCellWithIndexPath:indexPath];    attrs.transform3D = CATransform3DMakeRotation(arc4random_uniform(M_1_PI), 1, 1, 1);    // zIndex越大，就越在上面    attrs.zIndex =  [self.collectionView numberOfItemsInSection:indexPath.section]-indexPath.item;    @property (nonatomic) CGRect frame;    @property (nonatomic) CGPoint center;    @property (nonatomic) CGSize size;    @property (nonatomic) CATransform3D transform3D;    @property (nonatomic) CGRect bounds NS_AVAILABLE_IOS(7_0);    @property (nonatomic) CGAffineTransform transform NS_AVAILABLE_IOS(7_0);    @property (nonatomic) CGFloat alpha;    @property (nonatomic) NSInteger zIndex; // default is 0    @property (nonatomic, getter=isHidden) BOOL hidden; // As an optimization, UICollectionView might not create a view for items whose hidden attribute is YES    @property (nonatomic, strong) NSIndexPath *indexPath;    return attrs;    //    ABS(1-2);绝对值     CGRectIntersectsRect(<#CGRect rect1#>, <#CGRect rect2#>) 这要和rect1相交就都算；}- (NSArray<UICollectionViewLayoutAttributes *> *)layoutAttributesForElementsInRect:(CGRect)rect{    NSMutableArray *array = [NSMutableArray array];    NSInteger count = [self.collectionView numberOfItemsInSection:0];    for (int i=0; i<count; i++) {        UICollectionViewLayoutAttributes *attrs = [self layoutAttributesForItemAtIndexPath:[NSIndexPath indexPathForItem:i inSection:0]];        [array addObject:attrs];    }    return array;}- (BOOL)shouldInvalidateLayoutForBoundsChange:(CGRect)newBounds{    return YES;}从写方法计算contentsize
注：参考自http://my.oschina.net/u/2340880/blog/522682
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