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

Question

Hi i am beginner in ios and in my project have to create UICollectionView with adding UIHeader as like how we are adding UItableView Header but according to my code UIHeader is not adding for CollectionView please help me some one

my code:-

#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

it may help you

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

Maybe you need return the size of the header in

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