Question

使用核心数据填充我的表格视图。我没有得到的是如何从核心数据中删除单个条目。

我使用的是uitableview而不是控制器。

以下是我正在使用的代码：

-(UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {

if (tableView == favouritesTable) {
    cellValue = [licensePlateArray objectAtIndex:indexPath.row];
} else { // handle search results table view
    cellValue = [filteredListItems objectAtIndex:indexPath.row];
}

static NSString *CellIdentifier = @"vlCell";

VehicleListCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];

if (cell == nil) {

    NSLog(@"Cell Created");

    NSArray *nibObjects = [[NSBundle mainBundle] loadNibNamed:@"VehicleListCell" owner:nil options:nil];

    for (id currentObject in nibObjects) {
        if ([currentObject isKindOfClass:[VehicleListCell class]]) {
            cell = (VehicleListCell *)currentObject;
        }
    }

    UILongPressGestureRecognizer *pressRecongnizer = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(tableCellPressed:)];
pressRecongnizer.view.tag = indexPath.row;
    pressRecongnizer.minimumPressDuration = 0.5f;
    [cell addGestureRecognizer:pressRecongnizer];
    [pressRecongnizer release];
}

cell.textLabel.font = [UIFont systemFontOfSize:10];

Favouritesdata *favdata = [licensePlateArray objectAtIndex:indexPath.row];

[[cell ignition] setImage:[UIImage imageNamed:@"ignition.png"]];
[[cell direction] setImage:[UIImage imageNamed:@"south.png"]];

cell.licPlate.text = [favdata licenseplate];

NSLog(@"cellvalue for cellforRow: %@", cell.licPlate.text);

return cell;}

在UILongPressGestureRecognizer的方法中：

- (void)tableCellPressed:(UILongPressGestureRecognizer *)recognizer{

if (recognizer.state != UIGestureRecognizerStateBegan) {
    return;
}

VehicleListCell* cell = (VehicleListCell *)[recognizer view];

cellValueForLongPress = cell.licPlate.text;

NSLog(@"cell value: %@", cellValueForLongPress);

UIAlertView *alert = [[UIAlertView alloc] initWithTitle:nil message:nil delegate:self cancelButtonTitle:@"Cancel" otherButtonTitles: nil] ;
alert.tag = recognizer.view.tag;
[alert addButtonWithTitle:@"Remove from Favourites"];
[alert addButtonWithTitle:@"Take to Map"];

[alert show];}

此处在警报视图方法中，所选行将被删除（如果（[title isEqualToString：@“从收藏夹中删除”]））：

-(void)alertView:(UIAlertView *)alert clickedButtonAtIndex:(NSInteger)buttonIndex {

NSString *title = [alert buttonTitleAtIndex:buttonIndex];

NSManagedObjectContext *contextFav = [app managedObjectContext];
Favouritesdata * favourites = [NSEntityDescription insertNewObjectForEntityForName:@"Favouritesdata" inManagedObjectContext:contextFav];

if([title isEqualToString:@"Remove from Favourites"])
{
    NSLog(@"cellValueForLongPress: %@", cellValueForLongPress);
///////// to remove the object from core data
    [licensePlateArray removeObjectAtIndex:alert.tag];

}
else if([title isEqualToString:@"Take to Map"])
{
    NSLog(@"Go to MapView");
}

NSError *error;

if (![context save:&error]) {
    NSLog(@"Error Occured");
}
[favouritesTable reloadData];}

Answer 1

在cellForRowAtIndexPath

中写下来

    UILongPressGestureRecognizer *pressRecongnizer = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(tableCellPressed:)];
    pressRecongnizer.view.tag = indexPath.row;
    pressRecongnizer.minimumPressDuration = 0.5f;
    [cell addGestureRecognizer:pressRecongnizer];
    [pressRecongnizer release];

并使用像这样的alertview

UIAlertView *alert = [[UIAlertView alloc] initWithTitle:nil message:nil delegate:self cancelButtonTitle:@"Cancel" otherButtonTitles: nil] ;
alert.tag = recognizer.view.tag;
[alert addButtonWithTitle:@"Remove from Favourites"];
[alert addButtonWithTitle:@"Take to Map"];    
[alert show];

然后在-(void)alertView:(UIAlertView *)alert clickedButtonAtIndex:(NSInteger)buttonIndex

中写下来

[YourArray removeObjectAtIndex:alert.tag];    
[YourTable reloadData];

请在代码中的适当位置使用此代码..

快乐编码..

通过在表视图上选择一行来删除核心数据条目

1 个答案: