UICollectionView 的使用

#import "ViewController.h"

#define KscreenHeigh [[UIScreen mainScreen] bounds].size.height

#define KscreenWidth [[UIScreen mainScreen] bounds].size.width

// 注意const的位置

static NSString *const cellId = @"cell";

static NSString *const headerId = @"header";

static NSString *const footerId = @"footer";

@interface ViewController ()<UICollectionViewDelegate,UICollectionViewDataSource,UICollectionViewDelegateFlowLayout>

{

CGFloat cellWidth;

NSMutableArray *_section0Array;

}

@property(nonatomic,strong)UICollectionView *collectionView;

@end

@implementation ViewController


 1 - (void)viewDidLoad {
 2     [super viewDidLoad];
 3     self.view.backgroundColor = [UIColor cyanColor];
 4     _section0Array = [NSMutableArray arrayWithCapacity:10];
 5     _section0Array =[NSMutableArray arrayWithArray:@[@"1",@"2",@"3",@"4"]];
 6     cellWidth = KscreenWidth/4-10;
 7     UICollectionViewFlowLayout  *layout = [[UICollectionViewFlowLayout alloc]init];
 8     _collectionView = [[UICollectionView alloc]initWithFrame:CGRectMake(0, 64, KscreenWidth, KscreenHeigh-64) collectionViewLayout:layout];
 9     _collectionView.delegate = self;
10     _collectionView.dataSource = self;
11     [self.view addSubview:_collectionView];
12     _collectionView.backgroundColor = [UIColor whiteColor];
14     // 注册cell、sectionHeader、sectionFooter
15     [_collectionView registerClass:[UICollectionViewCell class] forCellWithReuseIdentifier:cellId];
16     [_collectionView registerClass:[UICollectionReusableView class] forSupplementaryViewOfKind:UICollectionElementKindSectionHeader withReuseIdentifier:headerId];
17     [_collectionView registerClass:[UICollectionReusableView class] forSupplementaryViewOfKind:UICollectionElementKindSectionFooter withReuseIdentifier:footerId];
18 }

实现数据源delegate

 1 #pragma mark ---- UICollectionViewDataSource
 2 // 设置section数量
 3 - (NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView
 4 {
 5     return 2;
 6 }
 7 // 设置每个section里有多少item
 8 - (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section
 9 {
10     return _section0Array.count;
11 }
12 // 设置cell ，可自定义UICollectionViewCell
13 - (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
14 {
15     UICollectionViewCell *cell = [_collectionView dequeueReusableCellWithReuseIdentifier:cellId forIndexPath:indexPath];
16     cell.backgroundColor = [UIColor greenColor];
17     return cell;
18 }
19 // 和UITableView类似，UICollectionView也可设置段头段尾
20 - (UICollectionReusableView *)collectionView:(UICollectionView *)collectionView viewForSupplementaryElementOfKind:(NSString *)kind atIndexPath:(NSIndexPath *)indexPath
21 {
22     if([kind isEqualToString:UICollectionElementKindSectionHeader])
23     {
24         UICollectionReusableView *headerView = [_collectionView dequeueReusableSupplementaryViewOfKind:kind withReuseIdentifier:headerId forIndexPath:indexPath];
25         if(headerView == nil)
26         {
27             headerView = [[UICollectionReusableView alloc] init];
28         }
29         headerView.backgroundColor = [UIColor grayColor];
30         
31         return headerView;
32     }
33     else if([kind isEqualToString:UICollectionElementKindSectionFooter])
34     {
35         UICollectionReusableView *footerView = [_collectionView dequeueReusableSupplementaryViewOfKind:kind withReuseIdentifier:footerId forIndexPath:indexPath];
36         if(footerView == nil)
37         {
38             footerView = [[UICollectionReusableView alloc] init];
39         }
40         footerView.backgroundColor = [UIColor lightGrayColor];
41         
42         return footerView;
43     }
44     return nil;
45 }
46 //允许移动item
47 - (BOOL)collectionView:(UICollectionView *)collectionView canMoveItemAtIndexPath:(NSIndexPath *)indexPath
48 {
49     return YES;
50 }
51 
52 //移动item从一个indexPath到另一个indexPath
53 - (void)collectionView:(UICollectionView *)collectionView moveItemAtIndexPath:(NSIndexPath *)sourceIndexPath toIndexPath:(NSIndexPath*)destinationIndexPath
54 {
55     
56 }

实现布局的delegate

 1 #pragma mark ---- UICollectionViewDelegateFlowLayout
 2 //设置item 大小
 3 - (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath *)indexPath
 4 {
 5     return (CGSize){cellWidth,cellWidth};
 6 }
 7 
 8 //每个分组的边缘尺寸
 9 - (UIEdgeInsets)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout insetForSectionAtIndex:(NSInteger)section
10 {
11     return UIEdgeInsetsMake(5, 5, 5, 5);
12 }
13 //每个分组的/行间距
14 
15 - (CGFloat)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout minimumLineSpacingForSectionAtIndex:(NSInteger)section
16 {
17     return 5.f;
18 }
19 
20 //每个分组的/列间距
21 
22 - (CGFloat)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout minimumInteritemSpacingForSectionAtIndex:(NSInteger)section
23 {
24     return 25.f;
25 }
26 //每个分组的头部尺寸
27 
28 - (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout referenceSizeForHeaderInSection:(NSInteger)section
29 {
30     return (CGSize){KscreenWidth,44};
31 }
32 
33 //每个分组的底部尺寸
34 
35 - (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout referenceSizeForFooterInSection:(NSInteger)section
36 {
37     return (CGSize){KscreenWidth,22};
38 }

其他不太常用的delegate

 1 #pragma mark ---- UICollectionViewDelegate
 2 
 3 - (BOOL)collectionView:(UICollectionView *)collectionView shouldHighlightItemAtIndexPath:(NSIndexPath *)indexPath
 4 {
 5     return YES;
 6 }
 7 
 8 // 点击高亮
 9 - (void)collectionView:(UICollectionView *)collectionView didHighlightItemAtIndexPath:(NSIndexPath *)indexPath
10 {
11     UICollectionViewCell *cell = [collectionView cellForItemAtIndexPath:indexPath];
12     cell.backgroundColor = [UIColor greenColor];
13 }
14 
15 
16 // 选中某item
17 - (void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath
18 {
19     
20 }
21 
22 
23 // 长按某item，弹出copy和paste的菜单
24 - (BOOL)collectionView:(UICollectionView *)collectionView shouldShowMenuForItemAtIndexPath:(NSIndexPath *)indexPath
25 {
26     return YES;
27 }
28 
29 // 使copy和paste有效
30 - (BOOL)collectionView:(UICollectionView *)collectionView canPerformAction:(SEL)action forItemAtIndexPath:(NSIndexPath *)indexPath withSender:(nullable id)sender
31 {
32     if ([NSStringFromSelector(action) isEqualToString:@"copy:"] || [NSStringFromSelector(action) isEqualToString:@"paste:"])
33     {
34         return YES;
35     }
36     
37     return NO;
38 }
39 
40 
41 - (void)collectionView:(UICollectionView *)collectionView performAction:(SEL)action forItemAtIndexPath:(NSIndexPath *)indexPath withSender:(nullable id)sender
42 {
43     if([NSStringFromSelector(action) isEqualToString:@"copy:"])
44     {
45         NSLog(@"-------------执行拷贝-------------");
46         [_collectionView performBatchUpdates:^{
47             [_section0Array removeObjectAtIndex:indexPath.row];
48             [_collectionView deleteItemsAtIndexPaths:@[indexPath]];
49         } completion:nil];
50     }
51     else if([NSStringFromSelector(action) isEqualToString:@"paste:"])
52     {
53         NSLog(@"-------------执行粘贴-------------");
54     }
55 }

附加长按移动的手势实现方法

//添加长按手势

UILongPressGestureRecognizer *longPress = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(longPress:)];

[self.collectionView addGestureRecognizer:longPress];

 1 - (void)longPress:(UILongPressGestureRecognizer *)longPress{
 2     UIGestureRecognizerState state = longPress.state;
 3     switch (state) {
 4         case UIGestureRecognizerStateBegan:{
 5             CGPoint pressPoint = [longPress locationInView:self.collectionView];
 6             NSIndexPath *indexPath = [self.collectionView indexPathForItemAtPoint:pressPoint];
 7             if (!indexPath) {
 8                 break;
 9             }
10             [self.collectionView beginInteractiveMovementForItemAtIndexPath:indexPath];
11             break;
12         }
13         case UIGestureRecognizerStateChanged:{
14             CGPoint pressPoint = [longPress locationInView:self.collectionView];
15             [self.collectionView updateInteractiveMovementTargetPosition:pressPoint];
16             break;
17         }
18         case UIGestureRecognizerStateEnded:{
19             [self.collectionView endInteractiveMovement];
20             break;
21         }
22         default:
23             [self.collectionView cancelInteractiveMovement];
24             break;
25     }
26 }

完毕