UIKit 框架之UICollectionView

1.自定义UICollectionViewCell

在myCollectionViewCell.h中声明两个属性

//
//  myCollectionViewCell.h
//  UICollectionView
//
//  Created by City--Online on 15/5/25.
//  Copyright (c) 2015年 XQB. All rights reserved.
//

#import <UIKit/UIKit.h>

@interface myCollectionViewCell : UICollectionViewCell
@property(nonatomic,strong) UIImageView *myImageView;
@property(nonatomic,strong) UILabel *nameLabel;
@end

在myCollectionViewCell.m中绘制视图

//
//  myCollectionViewCell.m
//  UICollectionView
//
//  Created by City--Online on 15/5/25.
//  Copyright (c) 2015年 XQB. All rights reserved.
//

#import "myCollectionViewCell.h"

@implementation myCollectionViewCell
-(void)layoutSubviews
{
    self.myImageView.frame=CGRectMake(0, 0, self.contentView.frame.size.width,80);
    [self.contentView addSubview:self.myImageView];

    self.nameLabel.frame = CGRectMake(0,80 , self.contentView.frame.size.width, 40);
    [self.contentView addSubview:self.nameLabel];
    [self.nameLabel setBackgroundColor:[UIColor cyanColor]];

}
@end

2.实例化UICollectionView,并实现它的代理方法

//
//  ViewController.m
//  UICollectionView
//
//  Created by City--Online on 15/5/25.
//  Copyright (c) 2015年 XQB. All rights reserved.
//

#import "ViewController.h"
#import "myCollectionViewCell.h"

@interface ViewController ()<UICollectionViewDataSource,UICollectionViewDelegate,UICollectionViewDelegateFlowLayout>
@property(nonatomic,strong) UICollectionView *collectionView;
@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];

    //UICollectionViewLayout可以说是UICollectionView的大脑和中枢，它负责了将各个cell、Supplementary View和Decoration Views进行组织，为它们设定各自的属性
    //Layout决定了UICollectionView是如何显示在界面上的。在展示之前，一般需要生成合适的UICollectionViewLayout子类对象，并将其赋予CollectionView的collectionViewLayout属性
    UICollectionViewFlowLayout  *collectionViewFlowLayout=[[UICollectionViewFlowLayout alloc]init];
    collectionViewFlowLayout.minimumInteritemSpacing=0.0;
    collectionViewFlowLayout.minimumLineSpacing=0.0;
    collectionViewFlowLayout.scrollDirection = UICollectionViewScrollDirectionVertical;
    collectionViewFlowLayout.sectionInset = UIEdgeInsetsMake(0.0, 0.0, 0, 0.0);
    //它定义了每一个item的大小。通过设定itemSize可以全局地改变所有cell的尺寸，如果想要对某个cell制定尺寸，可以使用-collectionView:layout:sizeForItemAtIndexPath:方法
    collectionViewFlowLayout.itemSize=CGSizeMake(120, 120);
    collectionViewFlowLayout.estimatedItemSize=CGSizeMake(120, 120);
    //由属性scrollDirection确定scroll view的方向，将影响Flow Layout的基本方向和由header及footer确定的section之间的宽度
    collectionViewFlowLayout.scrollDirection=UICollectionViewScrollDirectionVertical;
    //Header和Footer尺寸 同样地分为全局和部分。需要注意根据滚动方向不同，header和footer的高和宽中只有一个会起作用。垂直滚动时section间宽度为该尺寸的高，而水平滚动时为宽度起作用
    collectionViewFlowLayout.headerReferenceSize=CGSizeMake(100, 40);
    collectionViewFlowLayout.footerReferenceSize=CGSizeMake(100, 40);

    _collectionView=[[UICollectionView alloc]initWithFrame:self.view.bounds collectionViewLayout:collectionViewFlowLayout];
    _collectionView.backgroundColor=[UIColor whiteColor];
    _collectionView.delegate=self;
    _collectionView.dataSource=self;
    _collectionView.allowsSelection=YES;
    _collectionView.allowsMultipleSelection=YES;

    // 注册相关类
    [_collectionView registerClass:[myCollectionViewCell class] forCellWithReuseIdentifier:@"cell"];
    [_collectionView registerClass:[UICollectionReusableView class] forSupplementaryViewOfKind:UICollectionElementKindSectionHeader withReuseIdentifier:@"Header"];
    [_collectionView registerClass:[UICollectionReusableView class] forSupplementaryViewOfKind:UICollectionElementKindSectionFooter withReuseIdentifier:@"Footer"];
    //也可以用Nib
//    [[_collectionView registerNib:<#(UINib *)#> forCellWithReuseIdentifier:<#(NSString *)#>]
//    _collectionView registerNib:<#(UINib *)#> forSupplementaryViewOfKind:<#(NSString *)#> withReuseIdentifier:<#(NSString *)#>
    [self.view addSubview:_collectionView];

}

//UICollectionViewDataSource  代理
//每节单元格数
- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section
{
    if (section==0) {
        return 6;
    }
    else
    {
         return 4;
    }

}

//节数
- (NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView
{
    return 2;
}
//单元格
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
{
    myCollectionViewCell *cell =[collectionView dequeueReusableCellWithReuseIdentifier:@"cell" forIndexPath:indexPath];

    cell.backgroundColor = [UIColor colorWithRed:arc4random()%256/ 255.0  green:arc4random()%256 / 255.0 blue:arc4random()% 256 / 255.0  alpha:1];
    cell.myImageView=[[UIImageView alloc]initWithImage:[UIImage imageNamed:@"1.png"]];
    cell.nameLabel=[[UILabel alloc]init];
    cell.nameLabel.text=[NSString stringWithFormat:@"%ld %ld",indexPath.section,indexPath.row];
    return cell;

}
//节头节尾
- (UICollectionReusableView *)collectionView:(UICollectionView *)collectionView viewForSupplementaryElementOfKind:(NSString *)kind atIndexPath:(NSIndexPath *)indexPath
{
    if ([kind isEqualToString: UICollectionElementKindSectionFooter]) {
        UICollectionReusableView *footer=[collectionView dequeueReusableSupplementaryViewOfKind:kind withReuseIdentifier:@"Footer" forIndexPath:indexPath];
        footer.backgroundColor=[UIColor yellowColor];
        UILabel *label=[[UILabel alloc]initWithFrame:CGRectMake(0, 0, 100, 40)];
        label.text=@"label";
        label.textAlignment=NSTextAlignmentCenter;
        [footer addSubview:label];
        return footer;
    }
    else
    {
        UICollectionReusableView *Header=[collectionView dequeueReusableSupplementaryViewOfKind:kind withReuseIdentifier:@"Header" forIndexPath:indexPath];
        Header.backgroundColor=[UIColor blueColor];
        return Header;

    }
}
//UICollectionViewDelegate 代理
//选中时是否高亮
- (BOOL)collectionView:(UICollectionView *)collectionView shouldHighlightItemAtIndexPath:(NSIndexPath *)indexPath
{
    if (indexPath.row%2==0) {
        return YES;
    }
    return NO;
}
//选中高亮显示后
- (void)collectionView:(UICollectionView *)collectionView didHighlightItemAtIndexPath:(NSIndexPath *)indexPath
{
    NSLog(@"didHighlightItemAtIndexPath");
}
// 允许被选中
- (BOOL)collectionView:(UICollectionView *)collectionView shouldSelectItemAtIndexPath:(NSIndexPath *)indexPath
{
    return YES;
}
//允许被取消
- (BOOL)collectionView:(UICollectionView *)collectionView shouldDeselectItemAtIndexPath:(NSIndexPath *)indexPath
{
    return YES;
}
//选中某个单元格
- (void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath
{
     NSLog(@"didSelectItemAtIndexPath section=%ld row=%ld",indexPath.section,indexPath.row);
}
//取消某个单元格
- (void)collectionView:(UICollectionView *)collectionView didDeselectItemAtIndexPath:(NSIndexPath *)indexPath
{
    NSLog(@"didDeselectItemAtIndexPath section=%ld row=%ld",indexPath.section,indexPath.row);
}
//高亮不显示
- (void)collectionView:(UICollectionView *)collectionView didUnhighlightItemAtIndexPath:(NSIndexPath *)indexPath
{

    NSLog(@"didUnhighlightItemAtIndexPath");
}
//即将展示UICollectionViewCell
- (void)collectionView:(UICollectionView *)collectionView willDisplayCell:(UICollectionViewCell *)cell forItemAtIndexPath:(NSIndexPath *)indexPath
{
    NSLog(@"willDisplayCell");
}
//即将显示section的footer和header
- (void)collectionView:(UICollectionView *)collectionView willDisplaySupplementaryView:(UICollectionReusableView *)view forElementKind:(NSString *)elementKind atIndexPath:(NSIndexPath *)indexPath
{
     NSLog(@"willDisplaySupplementaryView");
}
//UICollectionViewCell显示完成
- (void)collectionView:(UICollectionView *)collectionView didEndDisplayingCell:(UICollectionViewCell *)cell forItemAtIndexPath:(NSIndexPath *)indexPath
{
    NSLog(@"didEndDisplayingCell");
}
//显示section的footer和header完成
- (void)collectionView:(UICollectionView *)collectionView didEndDisplayingSupplementaryView:(UICollectionReusableView *)view forElementOfKind:(NSString *)elementKind atIndexPath:(NSIndexPath *)indexPath
{
     NSLog(@"didEndDisplayingSupplementaryView");
}
//是否显示 copy、cut、paste等
- (BOOL)collectionView:(UICollectionView *)collectionView shouldShowMenuForItemAtIndexPath:(NSIndexPath *)indexPath
{
    return YES;
}
//是否显示action辅助功能
- (BOOL)collectionView:(UICollectionView *)collectionView canPerformAction:(SEL)action forItemAtIndexPath:(NSIndexPath *)indexPath withSender:(id)sender
{
    SEL sel=@selector(copy:);
    if (sel==action) {
        return YES;
    }
    return NO;
}
//判断选择的是什么action
- (void)collectionView:(UICollectionView *)collectionView performAction:(SEL)action forItemAtIndexPath:(NSIndexPath *)indexPath withSender:(id)sender
{
    SEL sel=@selector(copy:);
    if (sel==action) {
        NSLog(@"aaaaa");
    }

}

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

@end

在上面的Header、Footer没有自定义，其实也可以自定义。UICollectionView中的一些方法和UITableView中的类似,这里就不举例了。