无效更新：UICollectionView上的项目数无效 [英] Invalid update: invalid number of items on UICollectionView
问题描述
我很难过。这是我的情景。在我的Appdelegate中，我正在创建
I am stumped on this. Here is my scenario. In my Appdelegate, I am creating
- 视图控制器的一个实例，它将以模态方式呈现以从用户收集两个数据
- 一个tableView控制器
- 我以tableview控制器作为其根视图初始化的导航控制器
controller - 一个collectionviewController，请注意我也在这里注册了这个单元格的类。
- 我将导航控制器添加到第一个视图的UITabBarController和作为第二个视图的
集合视图。将TabBarCOntorller设置为的根视图窗口。
- An instance of a view controller that will be presented modally to collect two pieces of data from the user
- A tableView controller
- A navigation controller that I init with the tableview controller as its rootview
controller - A collectionviewController, note that I am registering the class for the cell here as well.
- A UITabBarController that I add the navigation controller to as the first view and the
collectionview to as the second view.. The TabBarCOntorller is set as the rootview of the window.
以下是代码：
- (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，用于显示模型查看控制器。模态视图控制器有一个按钮，该按钮从textField和datepicker获取值，并使用UserInfo字典中的值将其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。
The tableview has a navbar button that presents the model view controller. The modal view controller has a button that takes the values from a textField and a datepicker and posts that to the default notification center with the values in the UserInfo dictionary. The tableView contorller subscribes to the notification, puts the UserInfo dictionary in a MutableArray and updates the table. That works fine.
问题出在CollectionVIew上。 collectionVIew接收通知并调用目标方法来处理通知。我试图从通知中获取UserInfo字典并将新单元格添加到collectionView。
The problem is with the CollectionVIew. The collectionVIew receives the notification and calls a target method to handle the notification. I am trying to take the UserInfo dictionary from the notification and add a new cell to the collectionView.
但是......
当集合视图收到通知时，我收到错误：
When the collectionview receives the notification I get the error:
'无效更新：第0部分中的项目数无效。更新后的现有部分中包含的项目数（1）必须等于该部分中包含的项目数更新（1），加上或减去从该部分插入或删除的项目数（插入1个，删除0个），加上或减去移入或移出该部分的项目数（0移入，0移出） 。
'Invalid update: invalid number of items in section 0. The number of items contained in an existing section after the update (1) must be equal to the number of items contained in that section before the update (1), plus or minus the number of items inserted or deleted from that section (1 inserted, 0 deleted) and plus or minus the number of items moved into or out of that section (0 moved in, 0 moved out).'
以下是CollectionView的代码：
Here is the code for the CollectionView:
#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
我非常感谢能指出任何东西的人在这里.....
I would so much appreciate anyone who can point anything out here.....
推荐答案
这是使用 insertItemsAtIndexPaths 在空 UICollectionView 上。只需这样做：
It's a bug with using insertItemsAtIndexPaths on an empty UICollectionView. Just do this:
if (self.birthdays.count == 1) {
[self.collectionView reloadData];
} else {
[self.collectionView insertItemsAtIndexPaths:@[[NSIndexPath indexPathForItem: (self.birthdays.count -1) inSection:0]]];
}
（不能相信这在iOS8中仍然存在。）
(Can't believe this is still broken in iOS8.)
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