#import "ViewController.h"
#import "CustomViewCell.h"
#import "CollectionHeadView.h"
@interface ViewController ()<UICollectionViewDelegate, UICollectionViewDataSource, UICollectionViewDelegateFlowLayout>
@property (nonatomic, strong) UICollectionView *collectionView;
@end
@implementation ViewController
#pragma mark - life Cycle
- (void)viewDidLoad {
[super viewDidLoad];
self.title = @"HeaderCollectionView";
self.automaticallyAdjustsScrollViewInsets = NO;
self.navigationController.navigationBar.translucent = NO;
self.view.backgroundColor = [UIColor whiteColor];
[self setCollectionView];
[self setHeaderView];
}
#pragma mark - setUI
- (void)setCollectionView {
UICollectionViewFlowLayout *layout = [[UICollectionViewFlowLayout alloc]init];
layout.itemSize = CGSizeMake((self.view.frame.size.width - 30) / 3, (self.view.frame.size.width - 30) / 3);
self.collectionView = [[UICollectionView alloc]initWithFrame:self.view.bounds collectionViewLayout:layout];
self.collectionView.backgroundColor = [UIColor clearColor];
self.collectionView.delegate = self;
self.collectionView.dataSource = self;
// 最重要的一句代码!!!
self.collectionView.contentInset = UIEdgeInsetsMake(200, 0, 0, 0);
self.collectionView.autoresizingMask = UIViewAutoresizingFlexibleHeight | UIViewAutoresizingFlexibleWidth;
[self.view addSubview:self.collectionView];
// 注册cell
[self.collectionView registerClass:[UICollectionViewCell class] forCellWithReuseIdentifier:@"collectionCellIdentify"];
//xib创建的头视图
[self.collectionView registerNib:[UINib nibWithNibName:@"CollectionHeadView" bundle:nil] forSupplementaryViewOfKind:UICollectionElementKindSectionHeader withReuseIdentifier:@"headViewID"];
}
- (void)setHeaderView {
// 注意这里设置headerView的头视图的y坐标一定是从"负值"开始,因为headerView是添加在collectionView上的.
UIImageView *headerView = [[UIImageView alloc]initWithFrame:CGRectMake(0, -200, self.view.frame.size.width, 200)];
[headerView setImage:[UIImage imageNamed:@"1"]];
[self.collectionView addSubview:headerView];
}
#pragma mark - UICollectionViewDataSource
- (NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView {
return 10;
}
- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section {
return 5;
}
- (__kindof UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath {
UICollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:@"collectionCellIdentify" forIndexPath:indexPath];
cell.backgroundColor = [UIColor redColor];
return cell;
}
#pragma mark - UICollectionViewDelegateFlowLayout
- (UIEdgeInsets)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout insetForSectionAtIndex:(NSInteger)section {
return UIEdgeInsetsMake(0, 0, 0, 0);
}
#pragma mark - UICollectionViewDelegate
- (UICollectionReusableView *)collectionView:(UICollectionView *)collectionView viewForSupplementaryElementOfKind:(NSString *)kind atIndexPath:(NSIndexPath *)indexPath {
// 复用SectionHeaderView,SectionHeaderView是xib创建的
CollectionHeadView *headerView = [self.collectionView dequeueReusableSupplementaryViewOfKind:UICollectionElementKindSectionHeader withReuseIdentifier:@"headViewID" forIndexPath:indexPath];
UILabel *title = [[UILabel alloc]initWithFrame:CGRectMake(0, 0, headerView.frame.size.width, 40)];
title.font = [UIFont systemFontOfSize:15];
[headerView addSubview:title];
title.text = @"大型花展";
return headerView;
}
- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout referenceSizeForHeaderInSection:(NSInteger)section {
return CGSizeMake(self.view.frame.size.width, 30);
}
@end
