1

我在 4 个单元格中构建了一个带有固定 imageView 的 CollectionView 控制器。我希望 imageView 改变单元格选择。你能帮我做这个吗？

谢谢

这是我的代码

CollectionView 控制器 .m

……

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

-(NSInteger)collectionView:(UICollectionView *)collectionView
    numberOfItemsInSection:(NSInteger)section
{
    return 4;
}

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

    UIImage *image;

    int row = [indexPath row];

    image = [UIImage imageNamed:@"ICUbedGREEN.png"];

    myCell.imageView.image = image;

    return myCell;
}

我想在新闻上改变图像，但我无法弄清楚......

- (void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:    (NSIndexPath *)indexPath
{
    UIImage *image = [UIImage imageNamed:[NSString stringWithFormat:@"ICUbedRED.png"]];

    cell.imageView.image = .....

     NSLog(@"elementselected");

}

4

2 回答 2

1

在 UICollectionViewCell 的子类中实现 KVO 监听方法。如果要取消选择，请确保将多选设置为 true。

-(void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context{
 if ([keyPath isEqualToString@"selected"])
 {
      // check value of self.selected to know what you are currently.
      // change picture of image here
 }

}

在您的单元格初始化方法中，您需要将自己添加为侦听器，以便

 [self addObserver:self forKeyPath:@"selected" options:nil context:nil];
于 2013-01-02T18:59:06.743 回答
1

对于您的问题，这可能是最愚蠢的答案，但它对我有用。我不知道如何使用 Samuel 所说的 KEY 值路径。

基本上我做了一个 NSMutableArray 来存储图标的状态，红色或绿色..是或否..

selState = [[NSMutableArray alloc] initWithObjects:@"NO",@"NO",@"NO",@"NO",nil ];

然后在“ItemForIndexPath”方法中，检查为该项目设置图像的值

if ([[selState objectAtIndex:indexPath.row] isEqualToString:@"NO"]) {
    image = [UIImage imageNamed:@"ICUbedGREEN.png"];
}
else
{
    image = [UIImage imageNamed:@"ICUbedRED.jpg"];
}

选择项目时，使用 IndexPath 将 NO 的值更改为 YES，反之亦然。

if ([[selState objectAtIndex:indexPath.row] isEqualToString:@"NO"]) {
    [selState replaceObjectAtIndex:indexPath.row withObject:@"YES"];
}
else if ([[selState objectAtIndex:indexPath.row] isEqualToString:@"YES"]) {
    [selState replaceObjectAtIndex:indexPath.row withObject:@"NO"];
}

然后更新了集合视图

[self.collectionView reloadData];

所有代码都在这里

@interface ViewController (){
NSMutableArray *selState;
}
@end
@implementation ViewController

- (void)viewDidLoad
{
    [super viewDidLoad];
// Do any additional setup after loading the view.

    selState = [[NSMutableArray alloc] initWithObjects:@"NO",@"NO",@"NO",@"NO",nil ];
}

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

-(NSInteger)collectionView:(UICollectionView *)collectionView
numberOfItemsInSection:(NSInteger)section
{
    return 4;
}

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

    UIImage *image;


    if ([[selState objectAtIndex:indexPath.row] isEqualToString:@"NO"]) {
        image = [UIImage imageNamed:@"ICUbedGREEN.png"];
    }
    else
    {
        image = [UIImage imageNamed:@"ICUbedRED.jpg"];
    }


    myCell.imageView.image = image;

    return myCell;
}
- (void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:        (NSIndexPath *)indexPath
{
    if ([[selState objectAtIndex:indexPath.row] isEqualToString:@"NO"]) {
        [selState replaceObjectAtIndex:indexPath.row withObject:@"YES"];
    }
    else if ([[selState objectAtIndex:indexPath.row] isEqualToString:@"YES"]) {
        [selState replaceObjectAtIndex:indexPath.row withObject:@"NO"];
    }

    [self.collectionView reloadData];
}

@end

谢谢

编辑---->>

上面ItemForIndexPath中的代码也可以写成

image = [[selState objectAtIndex:indexPath.row] isEqualToString:@"NO"] ?
             [UIImage imageNamed:@"ICUbedGREEN.png"] : [UIImage imageNamed:@"ICUbedRED.jpg"];

结束编辑

于 2013-01-03T01:41:24.817 回答