UICollectionview 不工作，我没有得到任何 Cell

Question

我正在尝试使用集合视图并重用集合视图单元格，我必须从尚未启动的服务器获取 23 张图像和名称，因为我面临的问题

这是我的自定义单元格文件集合视图文件目标c

下面是我的自定义 cell.h

#import <UIKit/UIKit.h>

@interface CustomCell : UICollectionViewCell

{
    UIImageView *imageView;
}

@property (nonatomic, retain) UIImageView *imageView; //this imageview   is the only thing we need right now.


@end

这是我的自定义 cell.m 文件

#import "CustomCell.h"

@implementation CustomCell

@synthesize imageView;

- (id)initWithFrame:(CGRect)aRect
{
    if (self = [super initWithFrame:aRect])
    {
    //we create the UIImageView in this overwritten init so that we always have it at hand.
    imageView = [[UIImageView alloc] init];
    //set specs and special wants for the imageView here.
    [self addSubview:imageView]; //the only place we want to do this addSubview: is here!

    //You wanted the imageView to react to touches and gestures. We can do that here too.
    UITapGestureRecognizer * tap=[[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(onButtonTapped:)];
    [tap setNumberOfTapsRequired:1];
    [self addGestureRecognizer:tap];


    //We can also prepare views with additional contents here!
    //just add more labels/views/whatever you want.
    }
    return self;
    }

    -(void)onButtonTapped:(id)sender
    {
     //the response to the gesture.
     //mind that this is done in the cell. If you don't want things to happen from this cell.
     //then you can still activate this the way you did in your question.  
     }
 @end

这些是我的普通视图 controller.m 文件中的方法

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

    [[[cell contentView] subviews] makeObjectsPerformSelector:@selector(removeFromSuperview)];


    // create a uiview where we can place all views that need to go into this cell
    UIView * contents=[[UIView alloc]      initWithFrame:cell.contentView.bounds];
    [contents setBackgroundColor:[UIColor clearColor]];
    [cell.contentView addSubview:contents];


    // set tag to the indexPath.row so we can access it later
    [cell setTag:indexPath.row];

    // add interactivity
    UITapGestureRecognizer * tap=[[UITapGestureRecognizer alloc]  initWithTarget:self action:@selector(onButtonTapped:)];
    [tap setNumberOfTapsRequired:1];
    [cell addGestureRecognizer:tap];


if (cell.selected) {
    cell.backgroundColor = [UIColor blueColor]; // highlight selection
}
else
{
    cell.backgroundColor = [UIColor redColor]; // Default color
}
return cell;
}

-(void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath  {

    UICollectionViewCell *datasetCell =[collectionView cellForItemAtIndexPath:indexPath];
    datasetCell.backgroundColor = [UIColor blueColor]; // highlight selection
}

-(void)collectionView:(UICollectionView *)collectionView didDeselectItemAtIndexPath:(NSIndexPath *)indexPath {

UICollectionViewCell *datasetCell =[collectionView cellForItemAtIndexPath:indexPath];
datasetCell.backgroundColor = [UIColor redColor]; // Default color
}

当我移动到这个视图时，我没有得到任何单元格，它只是空白的背景图像，我什至给出了一张空白图片来查看视图的情况，但我什么也没得到，请帮助！ ！

Answer 1

单元格未显示，因为您可能没有正确设置数据源和委托。 由于您已在情节提要中添加了单元格，因此您无需在集合视图单元格中添加图像视图作为子视图。 首先将您在storyboard中添加的imageview的出口连接到CustomCell。然后删除

{
    UIImageView *imageView;
}

@property (nonatomic, retain) UIImageView *imageView;

你可以去掉- (id)initWithFrame:(CGRect)aRect这个方法，你可以在awakeFromNib方法中添加点击手势初始化

-(void)awakeFromNib {
  UITapGestureRecognizer * tap=[[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(onButtonTapped:)];
    [tap setNumberOfTapsRequired:1];
    [self addGestureRecognizer:tap];
}

没必要

 imageView = [[UIImageView alloc] init];
    [self addSubview:imageView]; 

再次在 cellForItemAtIndexPath 中 删除以下行

[[[cell contentView] subviews] makeObjectsPerformSelector:@selector(removeFromSuperview)];
UIView * contents=[[UIView alloc]      initWithFrame:cell.contentView.bounds];
[contents setBackgroundColor:[UIColor clearColor]];
[cell.contentView addSubview:contents];

进行这些更改后，请重试