如何在iOS中以编程方式为UICollectionView添加HeaderView

Question

嗨，我是ios的初学者，在我的项目中必须添加UIHeader来创建UICollectionView ，就像我们添加UItableView Header一样，但是根据我的代码， UIHeader没有为CollectionView添加，请帮助我

我的代码：

#import "ViewController.h"

@interface ViewController ()
{
     UICollectionView *_collectionView;
}

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];

    UICollectionViewFlowLayout *layout=[[UICollectionViewFlowLayout alloc] init];

    _collectionView = [[UICollectionView alloc]initWithFrame:CGRectMake(0, 10, 320, 480) collectionViewLayout:layout];

    [_collectionView setDataSource:self];
    [_collectionView setDelegate:self];

    [_collectionView registerClass:[UICollectionViewCell class] forCellWithReuseIdentifier:@"cellIdentifier"];

    [_collectionView registerClass:[UICollectionReusableView class] forSupplementaryViewOfKind:UICollectionElementKindSectionHeader withReuseIdentifier:@"HeaderView"];

    [_collectionView setBackgroundColor:[UIColor clearColor]];
    self.view.backgroundColor = [UIColor whiteColor];

    [self.view addSubview:_collectionView];
}

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

    return 15;
}

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

    UICollectionViewCell *cell=[collectionView dequeueReusableCellWithReuseIdentifier:@"cellIdentifier" forIndexPath:indexPath];

    cell.backgroundColor=[UIColor greenColor];

    return cell;
}

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

    return CGSizeMake(50, 50);
}

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

    UIEdgeInsets insets=UIEdgeInsetsMake(10, 10, 10, 10);
    return insets;
}

-(UICollectionReusableView *)collectionView:(UICollectionView *)collectionView viewForSupplementaryElementOfKind:(NSString *)kind atIndexPath:(NSIndexPath *)indexPath{

    if (kind == UICollectionElementKindSectionHeader) {

        UICollectionReusableView *reusableview = [collectionView dequeueReusableSupplementaryViewOfKind:UICollectionElementKindSectionHeader withReuseIdentifier:@"HeaderView" forIndexPath:indexPath];
        reusableview.backgroundColor = [UIColor redColor];

        if (reusableview==nil) {

            reusableview=[[UICollectionReusableView alloc] initWithFrame:CGRectMake(0, 0, 320, 50)];
        }

        UILabel *label=[[UILabel alloc] initWithFrame:CGRectMake(0, 0, 50, 10)];
        label.text= @"Hellow orld";
        [reusableview addSubview:label];
        return reusableview;
    }
    return nil;
}

@end

Answer 1

它可以帮助你

self.collectionView  =  [[UICollectionView alloc] initWithFrame:CGRectMake(0, 0, 320, self.view.frame.size.height) collectionViewLayout:flowlayout];
self.collectionView.contentInset = UIEdgeInsetsMake(50, 0, 0, 0);
UIView *headerView = [[UIView alloc]init];
headerView.frame = CGRectMake(0, -50, 320, 50);
[self.collectionView addSubview: headerView];
[self.view addSubview: _collectionView];

Answer 2

也许您需要返回标头的大小

    func collectionView(collectionView: UICollectionView, layout collectionViewLayout: MyFlowLayout, referenceSizeForHeaderInSection section: Int) -> CGSize {
        return CGSize(width: xx, height: xx)
    }