Question

我正在尝试显示我的收藏视图，但我得到的只是黑屏。我知道我在某个地方遗失了一些东西，但我似乎无法找到它是什么。

#import "StoreCollectionViewController.h"
#import "StoreItemCell.h"

@interface StoreCollectionViewController ()

@property (nonatomic, strong) NSMutableArray *productsArray;
@property (nonatomic, strong) UIActivityIndicatorView *loadingIndicator;

@end

@implementation StoreCollectionViewController

static NSString * const reuseIdentifier = @"Cell";

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self)
    {
        self.productsArray = [[NSMutableArray alloc]init];
    }
    return self;
}

- (void)viewDidLoad {
    [super viewDidLoad];

    self.collectionView.delegate = self;
    self.collectionView.dataSource = self;

    // Register cell classes
    [self.collectionView registerClass:[StoreItemCell class] forCellWithReuseIdentifier:reuseIdentifier];

    CGFloat width = CGRectGetWidth(self.view.bounds);
    CGFloat height = CGRectGetHeight(self.view.bounds);

    self.loadingIndicator = [[UIActivityIndicatorView alloc]initWithFrame:CGRectMake(width / 2, height / 2, 37, 37)];
    self.loadingIndicator.center = CGPointMake(width / 2, height / 2 - 37);
    self.loadingIndicator.autoresizingMask = (UIViewAutoresizingFlexibleRightMargin | UIViewAutoresizingFlexibleLeftMargin | UIViewAutoresizingFlexibleBottomMargin | UIViewAutoresizingFlexibleTopMargin);
    self.loadingIndicator.activityIndicatorViewStyle = UIActivityIndicatorViewStyleWhiteLarge;
    self.loadingIndicator.hidesWhenStopped = YES;
    [self.view addSubview:self.loadingIndicator];
    [self.loadingIndicator startAnimating];

    [self dispatch];
}

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

- (void)dispatch {
    NSURL *url = [NSURL URLWithString:@"http://api.bigcartel.com/littleheart/products.json"];
    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
        NSData *data = [NSData dataWithContentsOfURL:url];

        dispatch_async(dispatch_get_main_queue(), ^{
            if (data == nil) {
                NSLog(@"data is nil");
                UIAlertView *nilDataAlert = [[UIAlertView alloc]initWithTitle:@"" message:@"There is nothing here!" delegate:self cancelButtonTitle:@"OK" otherButtonTitles:nil, nil];
                [nilDataAlert show];

                [self.loadingIndicator stopAnimating];
            }
            else {
                [self performSelectorOnMainThread:@selector(getProducts:) withObject:data waitUntilDone:YES];
            }
        });
    });
}

- (void)getProducts:(NSData *)responseData {
    NSError *error;
    NSMutableArray *responseArray = [NSJSONSerialization
                                     JSONObjectWithData:responseData
                                     options:kNilOptions
                                     error:&error];

    for (NSDictionary *productDictionary in responseArray) {
        [self.productsArray addObject:productDictionary];
    }

    [self.collectionView reloadData];
    [self.loadingIndicator stopAnimating];
}

#pragma mark <UICollectionViewDataSource>

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

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

- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath {
    StoreItemCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:reuseIdentifier forIndexPath:indexPath];

    // Configure the cell
    NSString *productName = [[self.productsArray objectAtIndex:indexPath.row]objectForKey:@"name"];
    cell.itemNameLabel.text = productName;

    return cell;
}

#pragma mark <UICollectionViewDelegate>

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

}

@end

Answer 1

您是否使用 UICollectionViewDelegateFlowLayout 方法调整单元格大小。？

喜欢这个（这是在Swift中，使用Objective-C syntex ），

func collectionView(collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAtIndexPath indexPath: NSIndexPath) -> CGSize
{
    return CGSizeMake(50,120); //use whatever you wants.
}

Answer 2

问题是我想不是你是否在集合中加载了一些东西，而是更通用的东西。这就是collectionViewController是否完全实例化以及是否正确加载。所有根视图控制器视图都具有默认的白色。但UIWindow类具有默认的黑色。如果你看到黑色，我怀疑寡妇是空的，

UICollectionViewController黑屏

2 个答案: