我很难过。这是我的场景。在我的 Appdelegate 中，我正在创建
- 一个视图控制器的实例，它将以模态方式呈现以从用户那里收集两条数据
- 一个 tableView 控制器
- 我使用 tableview 控制器作为其 rootview 控制器初始化的导航
控制器 - 一个collectionviewController，注意我在这里也注册了单元格的类。
- 我将导航控制器添加到的 UITabBarController 作为第一个视图，将
collectionview 添加到第二个视图。TabBarCONtorller 设置为窗口的根视图。
这是代码：
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:
(NSDictionary *)launchOptions
{
self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
self.evc = [[WTAEntryControllerViewController alloc] init];
WTATableView *tv = [[WTATableView alloc] initWithNibName:@"WTATableView" bundle:nil];
UINavigationController *nav = [[UINavigationController alloc]
initWithRootViewController:tv];
nav.tabBarItem.title = NSLocalizedString(@"Birthday List", nil);
nav.tabBarItem.image = [UIImage imageNamed:@"birthdaycake"];
WTACollectionViewController *cv = [[WTACollectionViewController alloc]
initWithCollectionViewLayout:[[UICollectionViewFlowLayout alloc] init]];
[cv.collectionView registerClass:[UICollectionViewCell class]
forCellWithReuseIdentifier:CellIdentifier];
cv.collectionView.backgroundColor = [UIColor whiteColor];
NSLog(@"cv instance %@", cv);
UITabBarController *tabController = [[UITabBarController alloc] init];
tabController.viewControllers = @[nav, cv];
self.window.rootViewController = tabController;
[self.window makeKeyAndVisible];
return YES
}
tableview 有一个导航栏按钮，用于显示模型视图控制器。模态视图控制器有一个按钮，该按钮从 textField 和 datepicker 中获取值，并将其与 UserInfo 字典中的值一起发布到默认通知中心。tableView 控制器订阅通知，将 UserInfo 字典放入 MutableArray 并更新表。这很好用。
问题出在 CollectionVIew 上。collectionVIew 接收通知并调用目标方法来处理通知。我正在尝试从通知中获取 UserInfo 字典并向 collectionView 添加一个新单元格。
但...
当 collectionview 收到通知时，我收到错误：
'无效更新：第0节中的项目数无效。更新后现有节中包含的项目数（1）必须等于更新前该节中包含的项目数（1），加上或减去从该部分插入或删除的项目数（1 插入，0 删除）加上或减去移入或移出该部分的项目数（0 移入，0 移出）。
下面是 CollectionView 的代码：
#import "WTACollectionViewController.h"
#import "UIColor+WTAExtensions.h"
#import "WTAAppDelegate.h"
#import "WTAEntryControllerViewController.h"
@interface WTACollectionViewController () <UICollectionViewDelegateFlowLayout>
@property (strong, nonatomic) NSMutableArray *birthdays;
@end
@implementation WTACollectionViewController
-(id)initWithCollectionViewLayout:(UICollectionViewLayout *)layout{
NSLog(@"Calling init on Collection");
if(!(self = [super initWithCollectionViewLayout:layout])){
return nil;
}
self.birthdays = [NSMutableArray array];
NSLog(@"Count of Birthdays at init %ld", (long)[self.birthdays count] );
self.title = NSLocalizedString(@"Birthday Grid", nil);
self.tabBarItem.image = [UIImage imageNamed:@"package"];
NSLog(@"cv instance getting notif %@", self);
[[NSNotificationCenter defaultCenter]
addObserver:self
selector:@selector(handleNotification:)
name:@"BirthdayAdded"
object:nil];
return self;
}
-(void)handleNotification:(NSNotification *)notification
{
[self.birthdays addObject:[notification userInfo]];
NSLog(@"Count of birthdays when the notification is received: %ld", (long)
[self.birthdays count]);
[self.collectionView insertItemsAtIndexPaths:@[[NSIndexPath indexPathForItem:
(self.birthdays.count -1) inSection:0]]];
}
- (void)viewDidLoad
{
[super viewDidLoad];
NSLog(@"Calling View Did Load on Collection");
}
- (NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView {
return 1;
}
- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:
(NSInteger)section{
NSLog(@"Count of birthdays in the number of items in section: %ld", (long)
[self.birthdays count]);
return [self.birthdays count];
}
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView
cellForItemAtIndexPath:(NSIndexPath *)indexPath {
NSLog(@"Calling the cell for index path method");
NSDictionary *dict = [[NSMutableDictionary alloc] init];
dict = self.birthdays[indexPath.item];
UICollectionViewCell *cell = [collectionView
dequeueReusableCellWithReuseIdentifier:CellIdentifier forIndexPath:indexPath];
NSAssert(cell != nil, @"Expected a Cell");
cell.contentView.backgroundColor = [UIColor randomColor];
return cell;
}
#define GAP (1.0f)
-(CGSize)collectionView:(UICollectionView *)collectionView layout:
(UICollectionViewLayout *)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath
*)indexPath {
CGFloat edgeLength = self.collectionView.frame.size.width / 4.0f - GAP;
return (CGSize) {.width = edgeLength, .height = edgeLength};
}
-(CGFloat)collectionView:(UICollectionView *)collectionView layout:
(UICollectionViewLayout *)collectionViewLayout minimumLineSpacingForSectionAtIndex:
(NSInteger)section{
return GAP;
}
-(CGFloat)collectionView:(UICollectionView *)collectionView layout:
(UICollectionViewLayout *)collectionViewLayout minimumInteritemSpacingForSectionAtIndex:
(NSInteger)section{
return GAP;
}
@end
我非常感谢任何能在这里指出任何事情的人......