UICollectionView基础

UICollectionViewFlowLayout *flowLayout= [[UICollectionViewFlowLayout alloc]init];
self.myCollectionView = [[UICollectionView alloc] initWithFrame:CGRectMake(20, 20, 250, 350) collectionViewLayout:flowLayout];
self.myCollectionView.backgroundColor = [UIColor grayColor];
[self.myCollectionView registerClass:[UICollectionViewCell class] forCellWithReuseIdentifier:@“myCell"];
self.myCollectionView.delegate = self;
self.myCollectionView.dataSource = self;

[self.view addSubview:self.myCollectionView];

@interface ViewController : UIViewController <UICollectionViewDelegateFlowLayout, UICollectionViewDataSource>

- (NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView
{
    return 2;
}

- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section
{
    return 7;
}

- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
{
    UICollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:@"myCell" forIndexPath:indexPath];
    if(indexPath.section==0)
    {
        cell.backgroundColor = [UIColor redColor];
    }
    else if(indexPath.section==1)
    {
        cell.backgroundColor = [UIColor greenColor];
    }
    return cell;
}

[self.myCollectionView registerClass:[MyHeadView class] forSupplementaryViewOfKind:UICollectionElementKindSectionHeader withReuseIdentifier:@"hxwHeader"];
[self.myCollectionView registerClass:[MyHeadView class] forSupplementaryViewOfKind:UICollectionElementKindSectionFooter withReuseIdentifier:@"hxwHeader"];

-(CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout referenceSizeForHeaderInSection:(NSInteger)section
{
    CGSize size = {240,25};
    return size;
}

-(CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout referenceSizeForFooterInSection:(NSInteger)section
{
    CGSize size = {240,25};
    return size;
}

- (UICollectionReusableView *)collectionView:(UICollectionView *)collectionView viewForSupplementaryElementOfKind:(NSString *)kind atIndexPath:(NSIndexPath *)indexPath
{
    MyHeadView *headView;
    
    if([kind isEqual:UICollectionElementKindSectionHeader])
    {
         headView = [collectionView dequeueReusableSupplementaryViewOfKind:UICollectionElementKindSectionHeader withReuseIdentifier:@"hxwHeader" forIndexPath:indexPath];
        [headView setLabelText:[NSString stringWithFormat:@"section %d‘s header",indexPath.section]];
    }
    else if([kind isEqual:UICollectionElementKindSectionFooter])
    {
        headView = [collectionView dequeueReusableSupplementaryViewOfKind:UICollectionElementKindSectionFooter withReuseIdentifier:@"hxwHeader" forIndexPath:indexPath];
        [headView setLabelText:[NSString stringWithFormat:@"section %d‘s footer",indexPath.section]];
    }
    return headView;
}

#import <UIKit/UIKit.h>

@interface MyHeadView : UICollectionReusableView
- (void) setLabelText:(NSString *)text;
@end

#import "MyHeadView.h"

@interface MyHeadView()

@property (strong, nonatomic) UILabel *label;

@end

@implementation MyHeadView

- (id)initWithFrame:(CGRect)frame
{
    self = [super initWithFrame:frame];
    if (self)
    {
        self.label = [[UILabel alloc] init];
        self.label.font = [UIFont systemFontOfSize:18];
        [self addSubview:self.label];
    }
    return self;
}

- (void) setLabelText:(NSString *)text
{
    self.label.text = text;
    [self.label sizeToFit];
}

@end

[self.myCollectionView registerNib:[UINib nibWithNibName:@"MyCollectionCell" bundle:nil] forCellWithReuseIdentifier:@"hxwCell"];

[self.myCollectionView registerNib:[UINib nibWithNibName:@"MySupplementaryView" bundle:nil] forSupplementaryViewOfKind:UICollectionElementKindSectionHeader withReuseIdentifier:@"hxwHeader"];
    
[self.myCollectionView registerNib:[UINib nibWithNibName:@"MySupplementaryView" bundle:nil] forSupplementaryViewOfKind:UICollectionElementKindSectionFooter withReuseIdentifier:@"hxwFooter"];

UICollectionReusableView *view =  [collectionView dequeueReusableSupplementaryViewOfKind :kind withReuseIdentifier:@"hxwHeader" forIndexPath:indexPath];

UILabel *label = (UILabel *)[view viewWithTag:1];

label.text = @"empty";

- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath *)indexPath
{
    if(indexPath.section==0 && indexPath.row==1)
    {
        return CGSizeMake(50, 50);
    }
    else
    {
        return CGSizeMake(75, 30);
    }
}

- (UIEdgeInsets)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout insetForSectionAtIndex:(NSInteger)section
{
    if(section==0)
    {
        return UIEdgeInsetsMake(35, 25, 15, 25);
    }
    else
    {
        return UIEdgeInsetsMake(15, 15, 15, 15);
    }
}

- (CGFloat)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout minimumLineSpacingForSectionAtIndex:(NSInteger)section
{
    if(section==0)
    {
        return 10.0;
    }
    else
    {
        return 20.0;
    }
}

- (CGFloat)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout minimumInteritemSpacingForSectionAtIndex:(NSInteger)section
{
    if(section==0)
    {
        return 10.0;
    }
    else
    {
        return 20.0;
    }
}

- (void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath
{
[self.myArray removeObjectAtIndex:indexPath.row];

[collectionView deleteItemsAtIndexPaths:[NSArray arrayWithObject:indexPath]];
}

- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
{
    UICollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:@"myCell" forIndexPath:indexPath];
    
    UIView* selectedBGView = [[UIView alloc] initWithFrame:cell.bounds];
    selectedBGView.backgroundColor = [UIColor blueColor];
    cell.selectedBackgroundView = selectedBGView;
    
    return cell;
}

- (BOOL)collectionView:(UICollectionView *)collectionView shouldHighlightItemAtIndexPath:(NSIndexPath *)indexPath
{
    return YES;
}

- (void)collectionView:(UICollectionView *)colView didHighlightItemAtIndexPath:(NSIndexPath *)indexPath
{
    UICollectionViewCell* cell = [colView cellForItemAtIndexPath:indexPath];
    
    [cell setBackgroundColor:[UIColor purpleColor]];
}

- (void)collectionView:(UICollectionView *)colView  didUnhighlightItemAtIndexPath:(NSIndexPath *)indexPath
{
    UICollectionViewCell* cell = [colView cellForItemAtIndexPath:indexPath];
    
    [cell setBackgroundColor:[UIColor yellowColor]];
}