从自定义 UICollectionViewCell 获取正确的按钮
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【中文标题】从自定义 UICollectionViewCell 获取正确的按钮【英文标题】:Get correct button from custom UICollectionViewCell 【发布时间】:2015-06-05 10:40:30 【问题描述】:我有一个带有自定义 UICollectionViewCell 的自定义 UICollectionView,我的单元格上有一个类似按钮(已连接到 CustomCVCell.h 文件),我需要在按下此按钮时更改它的背景。我所做的是在cellForItemAtIndexPath:
方法上声明按钮的操作,如下所示:
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
CollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:reuseIdentifier forIndexPath:indexPath];
// Configure the cell
FolderProducts *item = _feedItems[indexPath.item];
[cell.like addTarget:self action:@selector(likeProduct:) forControlEvents:UIControlEventTouchUpInside];
return cell;
然后在按钮操作上,我尝试像这样更改背景:
- (void)likeProduct:(UIButton *)button
[button setImage:[UIImage imageNamed:@"dislike.png"] forState:UIControlStateNormal];
它可以工作,但是其他随机单元格的类似按钮的图像发生了变化,我不明白为什么..
我还尝试使用以下方法检索正确的单元格:
CollectionViewCell *cell = (CollectionViewCell *)button.superview.superview;
然后:
[button setImage:[UIImage imageNamed:@"dislike.png"] forState:UIControlStateNormal];
但结果还是错了
【问题讨论】:
【参考方案1】:问题是由于reusing of the collection view cell
造成的,因为你得到了具有相同图像的随机按钮
解决方案是维护数组并存储liked
按钮的选定索引路径
例如你可以像下面那样做
在CustomCVCell.h
中定义一个自定义委托
#import <UIKit/UIKit.h>
@class CustomCVCell; //forword decleration
@protocol CustomCellDelegate <NSObject>
- (void)customCell:(CustomCVCell *)cell actionForButton:(UIButton *)inButton; //hear u are passing the cell and the button
@end
@interface CustomCVCell : UICollectionViewCell
@property (weak, nonatomic) IBOutlet UIButton *like ; //a button with outlet
@property (weak, nonatomic) id<CustomCellDelegate> cellDelegate;// define a custom delegate
- (IBAction)likeProduct:(UIButton *)sender; // set action to cell not in the controller
//... other code
@end
在CustomCVCell.m
#import "CustomCVCell.h"
@implementation CustomCVCell
- (id)initWithFrame:(CGRect)frame
self = [CustomCVCell cell];
if (self)
return self;
- (void)awakeFromNib
// Initialization code
//handle button action in the cell
- (IBAction)likeProduct:(UIButton *)sender
//this action you want it to be in controller, call a delegate method
if([self.cellDelegate respondsToSelector:@selector(customCell:actionForButton:)])
[self.cellDelegate customCell:self actionForButton:sender]; //implent the action in the controller
@end
在controller
- (void)viewDidLoad
[super viewDidLoad];
UICollectionViewFlowLayout *aFlowLayout = [[UICollectionViewFlowLayout alloc]init];
//..set up code
[_aCollectionView registerClass:[CustomCVCell class] forCellWithReuseIdentifier:@"CELL"];
likedCells = [[NSMutableArray alloc]init]; //to hold the index paths of the liked cells
//..other code
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
CustomCVCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:@"CELL" forIndexPath:indexPath];
if([likedCells containsObject:indexPath]) //based on the indexaths paths u can set the images of the liked cell and if not set nil
[cell.like setBackgroundImage:[UIImage imageNamed:@"22.jpg"] forState:UIControlStateNormal];
else
[cell.like setBackgroundImage:nil forState:UIControlStateNormal];
cell.backgroundColor = [UIColor greenColor]; //for testing
cell.cellDelegate = self; //this must be important
return cell;
//as the like button cliks this method will trigger since u are passing the cell and the button, u can get the index path of the cell
- (void)customCell:(CustomCVCell *)cell actionForButton:(UIButton *)inButton
//hear u will get both cell and its button
//[inButton setImage:[UIImage imageNamed:@"22.jpg"] forState:UIControlStateNormal];
[inButton setBackgroundImage:[UIImage imageNamed:@"22.jpg"] forState:UIControlStateNormal]; //set the image
[likedCells addObject: [_aCollectionView indexPathForCell:cell]]; //and store the index path in the likedCells array
如果你想反转操作同样删除索引路径就是这样
【讨论】:
【参考方案2】:基本思路是需要将buttons坐标空间转换为collectionviews坐标空间,然后获取indexPath。
如果你需要使用 Objective-C,让我们创建一个返回给定单元格子视图的 indexPath 的函数:
- (NSIndexPath *)indexPathForCellContainingView:(UIView *)view inCollectionView:(UICollectionView *)collectionView
CGPoint viewCenterRelativeToCollectionView = [collectionView convertPoint:CGPointMake(CGRectGetMidX(view.bounds), CGRectGetMidY(view.bounds)) fromView:view];
NSIndexPath *cellIndexPath = [collectionView indexPathForItemAtPoint:viewCenterRelativeToCollectionView];
return cellIndexPath
现在在您的按钮处理程序中:
- (void)likeProduct:(UIButton *)button
[button setImage:[UIImage imageNamed:@"dislike.png"] forState:UIControlStateNormal];
NSIndexPath *buttonIndexPath = [self indexPathForCellContainingView:button];
UICollectionViewCell *tappedCell = [collectionView cellForItemAtIndexPath:buttonIndexPath];
请记住,当您的单元格滚动到边界之外时,它将被重复使用,因此您肯定需要跟踪此状态。要么将其持久化到磁盘,要么拥有一个简单的 NSDictionary 来管理每个按钮的状态。
我在 Swift 中有一个方便的Gist,它也正好解决了 UICollectionView 和 UITableView 的问题。
here和here也有类似的问题
【讨论】:
【参考方案3】:为您的按钮分配一个标签以识别它。
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
CollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:reuseIdentifier forIndexPath:indexPath];
// Configure the cell
FolderProducts *item = _feedItems[indexPath.item];
[cell.like addTarget:self action:@selector(likeProduct:) forControlEvents:UIControlEventTouchUpInside];
cell.like.tag = indexPath.item;
return cell;
然后在实现方法中添加如下代码,
- (void)likeProduct:(UIButton *)button
UIButton *btn = (UIButton *)sender;
[button setImage:[UIImage imageNamed:@"dislike.png"] forState:UIControlStateNormal];
注意:实现多选/单选的最佳方式是通过与您的喜好相关联的 id。使用集合视图存储该 ID,然后从按钮方法重新加载表格。
如果您还需要更多帮助,请告诉我..
【讨论】:
完全没有必要!您可以通过将按钮的框架转换为集合视图来轻松提取 indexPath ***.com/a/30665133/1652402【参考方案4】:您可以在选择器中设置按钮标签和检索标签。
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
CollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:reuseIdentifier forIndexPath:indexPath];
// Configure the cell
FolderProducts *item = _feedItems[indexPath.item];
cell.like.tag = indexPath.item
[cell.like addTarget:self action:@selector(likeProduct:) forControlEvents:UIControlEventTouchUpInside];
return cell;
【讨论】:
那是不必要的,现在您可以在视图中隐式使用标签,有人可能会破坏它。而是将按钮框架转换为集合视图框架并以这种方式获取索引路径***.com/a/30665133/1652402【参考方案5】:因为您没有为单元格中的按钮设置标签。所以这些都是一次选择的。您可以设置他们的标签,如 indexPath.item 并在 didSelectItemAtIndexPath 中捕获他们的标签并选择所需的项目。
【讨论】:
不要将代码粘贴为图像,如果将其粘贴为文本,则 OP 更容易将其复制到他们的项目中 对不起,丹尼尔首先我试图粘贴我的代码。但是当我点击更新按钮时,它给了我一些错误,比如 4 个空格打算......以上是关于从自定义 UICollectionViewCell 获取正确的按钮的主要内容,如果未能解决你的问题,请参考以下文章