删除 UICollectionView 单元格时出现 NSRangeException

Question

我试图从 for.. in 循环中的 UICollectionView 中删除单元格，每次我得到 NSRangeException。我不明白为什么会这样，因为首先我对数组进行排序，然后尝试删除。所以问题是我首先尝试向服务器发送请求，只有当响应成功时，我的 UICollectionView 单元格和数组元素才会被删除。这是我的代码：

通过循环传递元素：

- (IBAction)deletePictures:(id)sender {
int i = 0;
if (selectedPhotosURL.count>0){
    loadCount = (int)selectedPhotosURL.count;
//sorting an array (it works fine)
    NSArray *indexPaths = sortMediaCollection.indexPathsForSelectedItems;
    NSMutableArray *pathes = [NSMutableArray arrayWithArray:indexPaths];
    NSSortDescriptor *highestToLowest = [NSSortDescriptor sortDescriptorWithKey:@"self" ascending:NO];
    [pathes sortUsingDescriptors:[NSArray arrayWithObject:highestToLowest]];
    [selecedCellsArray sortUsingComparator:^NSComparisonResult(NSString *str1, NSString *str2) {
        return [str2 compare:str1 options:(NSNumericSearch)];
    }];


    NSLog(@"selectedCElls %@",selecedCellsArray);
    for(NSIndexPath *indexPath in pathes) {
        NSLog(@"indexPath in pathes is %ld",(long)indexPath.row);
        AVMSMCell *cell = (AVMSMCell *)[sortMediaCollection cellForItemAtIndexPath:indexPath];
        AVMDataStore *oneItem = [smArray objectAtIndex:indexPath.row];
        NSString *contentId = oneItem.fileId;
        if (i<selectedPhotosURL.count){
            NSLog(@"indexPath second loop is %ld",(long)indexPath.row);
            [self deleteUserPhotos:contentId : indexPath.row : cell]; // send request to the server it's ok too.
            i++;
        }
    }

} else {
    [self selectAtLeastOneFirst];
  }

}

例如，这里我 select 6 个单元格和我的数组按正确的顺序从上到下排序 (5,4,3,2,1,0)。然后我按照这个顺序在方法中传递这个元素。

请求发送方式：

-(void)deleteUserPhotos : (NSString *)contentId : (NSInteger )pathRow : (AVMSMCell *) cell{
NSNumber *rowNsNum = [NSNumber numberWithUnsignedInt:(unsigned int)pathRow];
if (([selecedCellsArray containsObject:[NSString stringWithFormat:@"%@",rowNsNum]]) ) 
{
    cell.selectedBG.backgroundColor = DANGER;
    [[UIApplication sharedApplication] setNetworkActivityIndicatorVisible:YES];
    AFHTTPRequestOperationManager *manager = [AFHTTPRequestOperationManager manager];
    NSString *token = [defaults objectForKey:@"token"];
    NSString *header = [NSString stringWithFormat:@"Bearer %@",token];
    NSDictionary *params = @{@"lang": @"en",@"content_id":contentId,@"project_id":[defaults objectForKey:@"project_id"]}; 
    manager.responseSerializer = [AFJSONResponseSerializer serializer];
    [manager.requestSerializer setValue:header forHTTPHeaderField:@"Authorization"];
    [manager POST:@"http://example.com/api/project/delete-content" parameters:params success:^(AFHTTPRequestOperation *operation, id responseObject) {
        [[UIApplication sharedApplication] setNetworkActivityIndicatorVisible:NO];
        NSLog(@"JSON: %@", responseObject);

        if ([[responseObject objectForKey:@"result"] isEqualToString:@"success"]){
            @try{
                NSLog(@"pathRow in TRY %ld",(long)pathRow); // HERE I get wrong number after two or three elements already passed
                [smArray removeObjectAtIndex:(unsigned int)pathRow];

                [selecedCellsArray removeObject:[NSString stringWithFormat:@"%ld",(long)pathRow]];

                cell.selectedBG.hidden = YES;
                [sortMediaCollection reloadSections:[NSIndexSet indexSetWithIndex:0]];
                loadCount--;

                }
            } @catch (NSException *e){
                NSLog(@"something is bad %@",e);
                [SVProgressHUD dismiss];
                if (smArray.count<pathRow-1){
                [smArray removeObjectAtIndex:(unsigned int)pathRow-1];
                } 
            } @finally {
                cell.selectedBG.hidden = YES;
                [sortMediaCollection reloadSections:[NSIndexSet indexSetWithIndex:0]];
            }
        } else {
            NSLog(@"can't delete photo!");
        }
    } failure:^(AFHTTPRequestOperation *operation, NSError *error) {
        [[UIApplication sharedApplication] setNetworkActivityIndicatorVisible:NO];
        NSLog(@"Error: %@", error);
        errorEndSpinner
    }];
    }
}

所以在上面的方法中，我在两个或三个元素已经通过后得到了错误的元素编号，即第一个元素是 5，然后是 4，然后是 2，3,1,0。此时我的 @catch 处理异常并尝试使用 [smArray removeObjectAtIndex:(unsigned int)pathRow-1]; 删除元素然后我得到 NSRangeException 和我的应用程序崩溃。我做错了什么？

Answer 1

我用 this 答案解决了我的问题，并对我的代码做了一点修改。我有一个 NSRangeException 因为我通过循环删除了我的 UICollectionView 项目。相反，我应该像这样立即使用多次删除：

    // Delete the items from the data source.
                    [self deleteItemsFromDataSourceAtIndexPaths:selectedItemsIndexPaths];

                        // Now delete the items from the collection view.
                    [sortMediaCollection deleteItemsAtIndexPaths:selectedItemsIndexPaths];

所以现在我的代码如下所示：

通过循环：

- (IBAction)deletePictures:(id)sender {
int i = 0;
if (selectedPhotosURL.count>0){
    [SVProgressHUD showWithStatus:@"Deleting" maskType:SVProgressHUDMaskTypeBlack];
    loadCount = (int)selectedPhotosURL.count;
    NSArray *indexPaths = sortMediaCollection.indexPathsForSelectedItems;
    NSMutableArray *pathes = [NSMutableArray arrayWithArray:indexPaths];
    NSSortDescriptor *highestToLowest = [NSSortDescriptor sortDescriptorWithKey:@"self" ascending:NO];
    [pathes sortUsingDescriptors:[NSArray arrayWithObject:highestToLowest]];
    [selecedCellsArray sortUsingComparator:^NSComparisonResult(NSString *str1, NSString *str2) {
        return [str2 compare:str1 options:(NSNumericSearch)];
    }];

    for(NSIndexPath *indexPath in pathes) {
        AVMSMCell *cell = (AVMSMCell *)[sortMediaCollection cellForItemAtIndexPath:indexPath];
        AVMDataStore *oneItem = [smArray objectAtIndex:indexPath.row];
        NSString *contentId = oneItem.fileId;
        if (i<selectedPhotosURL.count){
            [self deleteUserPhotos:contentId : indexPath.row : cell pathes:pathes]; //pass array with pathes into 'deleteUserPhotos'
            i++;
        }
    }

} else {
    [self selectAtLeastOneFirst];
   }

}

主要方法：

-(void)deleteItemsFromDataSourceAtIndexPaths:(NSArray  *)itemPaths {
NSMutableIndexSet *indexSet = [NSMutableIndexSet indexSet];
for (NSIndexPath *itemPath  in itemPaths) {
    [indexSet addIndex:itemPath.row];
}
[smArray removeObjectsAtIndexes:indexSet];
}

-(void)deleteUserPhotos : (NSString *)contentId : (NSInteger )pathRow : (AVMSMCell *) cell pathes:(NSMutableArray*)selectedItemsIndexPaths{
NSNumber *rowNsNum = [NSNumber numberWithUnsignedInt:(unsigned int)pathRow];
if (([selecedCellsArray containsObject:[NSString stringWithFormat:@"%@",rowNsNum]]))
{
    cell.selectedBG.backgroundColor = DANGER;
    [[UIApplication sharedApplication] setNetworkActivityIndicatorVisible:YES];
    AFHTTPRequestOperationManager *manager = [AFHTTPRequestOperationManager manager];
    NSString *token = [defaults objectForKey:@"token"];
    NSString *header = [NSString stringWithFormat:@"Bearer %@",token];
    NSDictionary *params = @{@"lang": @"en",@"content_id":contentId,@"project_id":[defaults objectForKey:@"project_id"]}; 
    manager.responseSerializer = [AFJSONResponseSerializer serializer];
    [manager.requestSerializer setValue:header forHTTPHeaderField:@"Authorization"];
    [manager POST:@"http://example.com/api/project/delete-content" parameters:params success:^(AFHTTPRequestOperation *operation, id responseObject) {
        [[UIApplication sharedApplication] setNetworkActivityIndicatorVisible:NO];
        NSLog(@"JSON: %@", responseObject);

        if ([[responseObject objectForKey:@"result"] isEqualToString:@"success"]){
            @try{

                [selecedCellsArray removeObject:[NSString stringWithFormat:@"%ld",(long)pathRow]];

                loadCount--;

                if (loadCount==0){ //only there remove items from collectionview

                        // Delete the items from the data source.
                    [self deleteItemsFromDataSourceAtIndexPaths:selectedItemsIndexPaths];
                        // Now delete the items from the collection view.
                    [sortMediaCollection deleteItemsAtIndexPaths:selectedItemsIndexPaths];

                    [selectedPhotosURL removeAllObjects];
                    }
            } @catch (NSException *e){
                NSLog(@"something is bad %@",e);
                [SVProgressHUD dismiss];
                if (smArray.count<pathRow-1){
                [smArray removeObjectAtIndex:(unsigned int)pathRow-1];
                }
            } @finally {
                cell.selectedBG.hidden = YES;
                [sortMediaCollection reloadSections:[NSIndexSet indexSetWithIndex:0]];
            }
        } else {
            NSLog(@"can't delete photo!");
        }
    } failure:^(AFHTTPRequestOperation *operation, NSError *error) {
        [[UIApplication sharedApplication] setNetworkActivityIndicatorVisible:NO];
        NSLog(@"Error: %@", error);
        errorEndSpinner
    }];
  }
}

希望这对某些人有所帮助。

Answer 2

我遇到了同样的错误，但发现它与具有数组镜像副本的不同 class 以及 class 访问已删除的索引有关。

您可以添加异常断点以准确查看异常的来源。有助于区分代码中的错误和来自 iOS SDK 的错误：

删除 UICollectionView 单元格时出现 NSRangeException

NSRangeException while deleting UICollectionView cells

objective-c

nsrangeexception

uicollectionview