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我有以下代码生成 UICollectionView。当您长按 UICollectionViewCell 时，会出现 UIActionSheet。

这有效，但只有一次。如果您关闭 UIActionSheet 并再次长按同一单元格，则不会发生任何事情。

任何想法我做错了什么？

#import "ProjectsListViewController.h"
#import <QuartzCore/QuartzCore.h>

@interface ProjectsListViewController ()

@end

@implementation ProjectsListViewController

@synthesize appDelegate;

- (void)viewDidLoad
{
    [super viewDidLoad];

    appDelegate = (AppDelegate *)[[UIApplication sharedApplication] delegate];

    // CREATE THE COLLECTION VIEW
    UICollectionViewFlowLayout *flowLayout = [[UICollectionViewFlowLayout alloc] init];

    [self setCollectionView:[[UICollectionView alloc] initWithFrame:CGRectMake(20, 54, [[self view] bounds].size.width - 40, [[self view] bounds].size.height) collectionViewLayout:flowLayout]];
    [[self collectionView] setDataSource:self];
    [[self collectionView] setDelegate:self];
    [self.view addSubview:self.collectionView];
    [self.collectionView registerClass:[UICollectionViewCell class] forCellWithReuseIdentifier:@"Cell"];
    [[self collectionView] setAutoresizingMask:UIViewAutoresizingFlexibleWidth];
}

- (NSInteger)collectionView:(UICollectionView *)view numberOfItemsInSection:(NSInteger)section
{
    return [[[appDelegate userSettingsDictionary] objectForKey:@"Projects"] count];
}

- (NSInteger)numberOfSectionsInCollectionView: (UICollectionView *)collectionView 
{
    return 1;
}

- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
{    
    UICollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:@"Cell" forIndexPath:indexPath];

    // CREATE A BACKGROUND VIEW FOR THE FOLDER IMAGE
    UIImage *image = [UIImage imageNamed:[NSString stringWithFormat:@"folder.png"]];
    UIView *background = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 122, 89)];
    [background setBackgroundColor:[UIColor colorWithPatternImage:image]];
    [cell addSubview:background];

    // SET THE CELL TEXT
    UILabel *cellLabel = [[UILabel alloc] initWithFrame:CGRectMake(0, 95, 130, 100)];
    [cellLabel setText:[[[[[appDelegate userSettingsDictionary] objectForKey:@"Projects"] objectAtIndex:[indexPath row]] objectForKey:@"Project Name"] uppercaseString]];

    // LISTEN FOR A LONG PRESS ON EACH FOLDER
    UILongPressGestureRecognizer *longPress = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(handleLongPress:)];
    [cell addGestureRecognizer:longPress];

    [cell addSubview:cellLabel];
    return cell;
}

// PRESENT AN ACTION SHEET WHEN A FOLDER HAS RECEIVED A LONG PRESS EVENT
- (void)handleLongPress:(UILongPressGestureRecognizer *)recognizer
{
    if ( [recognizer state] == UIGestureRecognizerStateBegan )
    {
        UIActionSheet *actionSheet = [[UIActionSheet alloc] initWithTitle:@"Select an action" delegate:self cancelButtonTitle:@"Cancel" destructiveButtonTitle:@"Delete" otherButtonTitles:@"Edit", nil];

        [actionSheet addGestureRecognizer:recognizer];

        // SET THE SELECTED FOLDER'S ROW NUMBER AS THE ACTIONSHEET TAG.  JUST A WAY OF LETTING THE DELETE METHOD KNOW WHICH FOLDER TO DELETE
        [actionSheet showInView:self.view];
    } 
}

// GET THE SIZE OF THE FOLDER IMAGE AND SET EACH COLLECTION VIEW ITEM SIZE TO FIT
- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath *)indexPath
{
    UIImage *image = [UIImage imageNamed:[NSString stringWithFormat:@"folder.png"]];
    return CGSizeMake(image.size.width, image.size.height + 50);
}


- (UIEdgeInsets)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout insetForSectionAtIndex:(NSInteger)section
{
    return UIEdgeInsetsMake(10, 10, 90, 10);
}

@end

谢谢

4

2 回答 2

5

实际上，我不久前尝试了类似的方法，并发现几乎整个方法都是错误的。

首先：您设置细胞的方式并不好。因为单元格是可重用的，但现在每次集合视图请求特定单元格时都添加子视图。您应该UICollectionViewCell在方法中子类化并添加子视图initWithCoder:。

然后只需在子类上为文本字段创建一个属性。然后在collectionView:cellForItemAtIndexPath:您只需将文本设置为标签text属性。

现在让我们修复手势识别器。您不应该为每个设置一个手势识别器UICollectionViewCell，而应该只为一个全局识别器。在viewDidLoad:你应该添加：

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

然后你应该把它改成handleLongPress:这样：

- (void)handleLongPress:(UILongPressGestureRecognizer *)gesture {
    if (gesture.state == UIGestureRecognizerStateBegan) {
        NSIndexPath *indexPath = [self.collectionView indexPathForItemAtPoint:[gesture locationInView:self.collectionView]];

        if (indexPath != nil) {
            self.currentIndexPath = indexPath;

            UIActionSheet *actionSheet = [[UIActionSheet alloc] initWithTitle:@"Select an action" delegate:self cancelButtonTitle:@"Cancel" destructiveButtonTitle:@"Delete" otherButtonTitles:@"Edit", nil];

            UICollectionViewCell *itemCell = [self.collectionView cellForItemAtIndexPath:indexPath];
            [action showFromRect:CGRectMake(0, 0, itemCell.frame.size.width, itemCell.frame.size.height) inView:itemCell animated:YES];
        }
    }
}

请注意，我没有添加将识别器添加到操作表的行，我不明白您为什么要这样做。您还应该添加一个名为currentIndexPath.

此刻一切都应该设置妥当。当您从操作表中获得响应时，只需使用self.currentIndexPath来确定要删除/编辑的项目。

于 2012-10-11T14:44:07.517 回答
1

在handleLongPress:您将手势识别器分配给操作表。

[actionSheet addGestureRecognizer:recognizer];

我不知道你为什么这样做，但手势识别器只能用于单个视图。此分配可能会从表格视图单元格中删除手势识别器，因此表格单元格上的长按手势不再起作用。

于 2012-10-11T12:42:29.643 回答