ios - Imageview 没有出现在以编程方式创建的 Collection View 中

Question

我很难弄清楚为什么 cell.imageview 属性不显示下面的 image。 UIImage 不为零，创建了单元格，如果我为单元格分配了背景，则会显示它，这证明我正在正确创建 collectionview 和我的单元格。我以编程方式创建我的 collectionview 并且不使用任何 IB 或 interface builder。我以前做过很多次，但我真的对这个感到挠头。

提前致谢。

    @interface MainViewController : UIViewController

    @property(strong, nonatomic) UICollectionView *collectionView;

    @end

    @interface MainViewController ()<
    UICollectionViewDataSource, UICollectionViewDelegate,
    UICollectionViewDelegateFlowLayout, UIGestureRecognizerDelegate>

    @property(nonatomic, strong) MHTransitionShowDetail *interactivePushTransition;
    @property(nonatomic) CGPoint lastPoint;
    @property(nonatomic) CGFloat startScale;
    @property(strong, nonatomic) NSMutableArray *carImages;

    @end

    @implementation MainViewController

    - (instancetype)init {
      self = [super init];
      if (self) {
      }
      return self;
    }

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

      _carImages = [@[
        @"chevy_small",
        @"mini_small",
        @"rover_small",
        @"smart_small",
        @"highlander_small",
        @"venza_small",
        @"volvo_small",
        @"vw_small",
        @"ford_small",
        @"nissan_small"
      ] mutableCopy];

      self.view = [[UIView alloc] initWithFrame:[[UIScreen mainScreen] bounds]];

      UICollectionViewFlowLayout *layout =
          [[UICollectionViewFlowLayout alloc] init];
      layout.itemSize = CGSizeMake(106, 106);
      layout.minimumLineSpacing = 1.0;
      layout.minimumInteritemSpacing = 1.0;
      self.collectionView = [[UICollectionView alloc] initWithFrame:self.view.frame
                                               collectionViewLayout:layout];
      [self.collectionView setDataSource:self];
      [self.collectionView setDelegate:self];
      self.collectionView.alwaysBounceVertical = YES;
      [self.collectionView setContentInset:UIEdgeInsetsMake(20, 10, 10, 10)];
      [self.collectionView registerClass:[IKGCollectionViewCell class]
              forCellWithReuseIdentifier:@"myCell"];
      self.collectionView.backgroundColor = [UIColor whiteColor];
      [self.view addSubview:self.collectionView];
    }

    - (void)didReceiveMemoryWarning {
      [super didReceiveMemoryWarning];
      // Dispose of any resources that can be recreated.
    }

    #pragma CollectionView & FlowLayout methods

    - (CGSize)collectionView:(UICollectionView *)collectionView
                      layout:(UICollectionViewLayout *)collectionViewLayout
      sizeForItemAtIndexPath:(NSIndexPath *)indexPath {
      return CGSizeMake(120, 120);
    }


    - (NSInteger)collectionView:(UICollectionView *)collectionView
         numberOfItemsInSection:(NSInteger)section {
      return self.carImages.count;
    }

    - (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView
                      cellForItemAtIndexPath:(NSIndexPath *)indexPath {
      IKGCollectionViewCell *cell =
          [collectionView dequeueReusableCellWithReuseIdentifier:@"myCell"
                                                    forIndexPath:indexPath];
      long row = [indexPath row];
      UIImage *image = [UIImage imageNamed:self.carImages[row]];
      cell.imageView.userInteractionEnabled = YES;
      cell.imageView.image = image;
      NSLog(@"cell.image view %@", image);
      // [self makeCell:(IKGCollectionViewCell *)cell atIndexPath:indexPath];

      return cell;
    }
}
@end

@interface IKGCollectionViewCell : UICollectionViewCell
@property(nonatomic, strong) UIImageView *imageView;

@end


@implementation IKGCollectionViewCell
- (id)initWithFrame:(CGRect)frame {
  self = [super initWithFrame:frame];
  if (self) {
    self.imageView = [[UIImageView alloc] initWithFrame:self.bounds];
    NSLog(@"self.bounds is %@", NSStringFromCGRect(self.bounds));
  }
  return self;
}

- (void)layoutSubviews {
  [super layoutSubviews];
  self.imageView.frame = self.contentView.bounds;
}

@end

Answer 1

您错过了将单元格的 imageView 添加为它的 subview 。

所以在cell的initWithFrame

- (id)initWithFrame:(CGRect)frame {
    self = [super initWithFrame:frame];
    if (self) {
        self.imageView = [[UIImageView alloc] initWithFrame:self.bounds];
        //Add imageView as subview
        [self addSubview:self.imageView];
        NSLog(@"self.bounds is %@", NSStringFromCGRect(self.bounds));
    }
    return self;
}