iOS UICollectionView之三(基本用法)
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#import <UIKit/UIKit.h> @interface AppDelegate : UIResponder <UIApplicationDelegate> @property (strong, nonatomic) UIWindow *window; @end
#import "AppDelegate.h" #import "RootViewController.h" @interface AppDelegate () @end @implementation AppDelegate - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions { self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]]; // Override point for customization after application launch. self.window.backgroundColor = [UIColor whiteColor]; self.window.rootViewController = [[RootViewController alloc] init]; [self.window makeKeyAndVisible]; return YES; } @end
#import <UIKit/UIKit.h> @interface RootViewController : UIViewController @end
#import "RootViewController.h" #import "ImageViewCell.h" #define SCREEN_WIDTH [UIScreen mainScreen].bounds.size.width #define SCREEN_HEIGHT [UIScreen mainScreen].bounds.size.height #define line_gap 10 #define interitem_gap 20 @interface RootViewController ()<UICollectionViewDataSource,UICollectionViewDelegate,UICollectionViewDelegateFlowLayout> { } @end static NSString *identifier = @"cell"; static NSString *headerIdentifier = @"header"; static NSString *flooterIdentifier = @"floot"; @implementation RootViewController - (void)viewDidLoad { [super viewDidLoad]; //创建布局对象 UICollectionViewFlowLayout *layout = [[UICollectionViewFlowLayout alloc] init]; // 设置滚动的方向 [layout setScrollDirection:UICollectionViewScrollDirectionVertical]; //行的间隙 layout.minimumLineSpacing = line_gap; //列的间隙 layout.minimumInteritemSpacing = 10; //item的大小 layout.itemSize = CGSizeMake((SCREEN_WIDTH - 2*line_gap)/3, 80); //创建collectionView UICollectionView *collectionView = [[UICollectionView alloc] initWithFrame:[[UIScreen mainScreen] bounds] collectionViewLayout:layout]; collectionView.backgroundColor = [UIColor greenColor]; // 设置代理 collectionView.dataSource = self; collectionView.delegate = self; //告诉系统将来需要创建什么样的cell(在获取cell之前必须先注册一个cell到系统中) [collectionView registerClass:[ImageViewCell class] forCellWithReuseIdentifier:identifier]; // 注册头视图 [collectionView registerClass:[UICollectionReusableView class] forSupplementaryViewOfKind:UICollectionElementKindSectionHeader withReuseIdentifier:headerIdentifier]; // 注册尾视图 [collectionView registerClass:[UICollectionReusableView class] forSupplementaryViewOfKind:UICollectionElementKindSectionFooter withReuseIdentifier:flooterIdentifier]; [self.view addSubview:collectionView]; } // 告诉系统一共有多少组 - (NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView{ return 1; } // 告诉系统第section组有多少行 - (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section{ return 30; } // 告诉系统indexPath的第Section组的item行显示什么内容 - (UICollectionViewCell*)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath{ ImageViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:identifier forIndexPath:indexPath]; cell.photo.image = [UIImage imageNamed:@"cellPhoto"]; return cell; } //返回头headerView的大小 - (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout referenceSizeForHeaderInSection:(NSInteger)section{ CGSize size = CGSizeMake(SCREEN_WIDTH, 100+line_gap); return size; } //返回头flooterView的大小 - (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout referenceSizeForFooterInSection:(NSInteger)section { CGSize size = CGSizeMake(SCREEN_WIDTH, 100+line_gap); return size; } // 头和尾部显示的内容 - (UICollectionReusableView*)collectionView:(UICollectionView *)collectionView viewForSupplementaryElementOfKind:(NSString *)kind atIndexPath:(NSIndexPath *)indexPath{ UICollectionReusableView *reusableView = nil; if (kind == UICollectionElementKindSectionHeader) { reusableView = [collectionView dequeueReusableSupplementaryViewOfKind:UICollectionElementKindSectionHeader withReuseIdentifier:headerIdentifier forIndexPath:indexPath]; UIImageView *headerPhoto = [[UIImageView alloc] initWithFrame:CGRectMake(0, 0, SCREEN_WIDTH, 100)]; headerPhoto.image = [UIImage imageNamed:@"headerPhoto"]; [reusableView addSubview:headerPhoto]; }else if (kind == UICollectionElementKindSectionFooter){ reusableView = [collectionView dequeueReusableSupplementaryViewOfKind:UICollectionElementKindSectionFooter withReuseIdentifier:flooterIdentifier forIndexPath:indexPath]; UIImageView *flooterPhoto = [[UIImageView alloc] initWithFrame:CGRectMake(0, line_gap, SCREEN_WIDTH, 100)]; flooterPhoto.image = [UIImage imageNamed:@"flooterPhoto"]; [reusableView addSubview:flooterPhoto]; } return reusableView; } - (void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath{ NSLog(@"==%lu",indexPath.row); } @end
#import <UIKit/UIKit.h> @interface ImageViewCell : UICollectionViewCell @property (nonatomic, strong) UIImageView *photo; @end
#import "ImageViewCell.h" @implementation ImageViewCell - (instancetype)initWithFrame:(CGRect)frame{ if (self = [super initWithFrame:frame]) { self.photo = [[UIImageView alloc] init]; self.photo.frame = self.bounds; [self addSubview:self.photo]; } return self; } @end
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