我有一个UIViewController和一个UICollectionViewController . 我使用以下内容将UICollectionViewController添加到UIViewController:
UICollectionViewFlowLayout* flowLayout = [[UICollectionViewFlowLayout alloc]init];
[flowLayout setScrollDirection:UICollectionViewScrollDirectionHorizontal];
self.toolsCollectionViewController = [[ToolsCollectionViewController alloc] initWithCollectionViewLayout:flowLayout];
self.toolsCollectionViewController.view.backgroundColor = [UIColor clearColor];
[self addChildViewController:self.toolsCollectionViewController];
[self.view addSubview:self.toolsCollectionViewController.view];
[self.toolsCollectionViewController didMoveToParentViewController:self];
问题是,当我添加集合时,我会看到一个纯黑色的屏幕,显示没有单元格
#import "ToolsCollectionViewController.h"
@interface ToolsCollectionViewController ()
@end
@implementation ToolsCollectionViewController
static NSString * const reuseIdentifier = @"Cell";
- (void)viewDidLoad {
[super viewDidLoad];
// Uncomment the following line to preserve selection between presentations
// self.clearsSelectionOnViewWillAppear = NO;
// Register cell classes
[self.collectionView registerClass:[ToolsCollectionViewCell class] forCellWithReuseIdentifier:reuseIdentifier];
// Do any additional setup after loading the view.
}
- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
/*
#pragma mark - Navigation
// In a storyboard-based application, you will often want to do a little preparation before navigation
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
// Get the new view controller using [segue destinationViewController].
// Pass the selected object to the new view controller.
}
*/
#pragma mark
- (NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView {
#warning Incomplete implementation, return the number of sections
return 1;
}
- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section {
#warning Incomplete implementation, return the number of items
return 10;
}
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath {
ToolsCollectionViewCell *cell = (ToolsCollectionViewCell *)[collectionView dequeueReusableCellWithReuseIdentifier:reuseIdentifier forIndexPath:indexPath];
NSLog(@"Cell");
// Configure the cell
return cell;
}
#pragma mark
/*
// Uncomment this method to specify if the specified item should be highlighted during tracking
- (BOOL)collectionView:(UICollectionView *)collectionView shouldHighlightItemAtIndexPath:(NSIndexPath *)indexPath {
return YES;
}
*/
/*
// Uncomment this method to specify if the specified item should be selected
- (BOOL)collectionView:(UICollectionView *)collectionView shouldSelectItemAtIndexPath:(NSIndexPath *)indexPath {
return YES;
}
*/
/*
// Uncomment these methods to specify if an action menu should be displayed for the specified item, and react to actions performed on the item
- (BOOL)collectionView:(UICollectionView *)collectionView shouldShowMenuForItemAtIndexPath:(NSIndexPath *)indexPath {
return NO;
}
- (BOOL)collectionView:(UICollectionView *)collectionView canPerformAction:(SEL)action forItemAtIndexPath:(NSIndexPath *)indexPath withSender:(id)sender {
return NO;
}
- (void)collectionView:(UICollectionView *)collectionView performAction:(SEL)action forItemAtIndexPath:(NSIndexPath *)indexPath withSender:(id)sender {
}
*/
@end
我已经创建了一个NSLog循环通过单元格,似乎工作正常 . 不知道我错过了什么 .
2 回答
可能有3种不同的情景 .
您实施的配色方案导致了问题
委托和数据源未正确调用 .
您的单元格不存在或重用标识符无效 .
您是否正确设置了collectionView的委托和dataSource?如果没有这两个,collectionView将显示为空,并且仅显示带有背景颜色的矩形 .
您最需要的是将以下内容放在
- (void)viewDidLoad
上面:self.collectionView.delegate = self; self.collectionView.dataSource = self;