Question

您好我正在尝试Xcode，我想从列表中删除项目。我可以显示删除按钮但是一旦点击删除按钮就不会删除。删除代码位于代码的末尾。删除部分代码中缺少某些内容，我不确定它是什么。

#import "ToDoListTableViewController.h"
#import "ToDoItem.h"
#import "AddToDoItemViewController.h"

@interface ToDoListTableViewController ()

@property NSMutableArray *toDoItems;

@end

@implementation ToDoListTableViewController

- (void)loadInitialData {
    ToDoItem *item1 = [[ToDoItem alloc] init];
    item1.itemName = @"Buy milk";
    [self.toDoItems addObject:item1];
    ToDoItem *item2 = [[ToDoItem alloc] init];
    item2.itemName = @"Buy eggs";
    [self.toDoItems addObject:item2];
    ToDoItem *item3 = [[ToDoItem alloc] init];
    item3.itemName = @"Read a book";
    [self.toDoItems addObject:item3];
}

- (IBAction)unwindToList:(UIStoryboardSegue *)segue {
    AddToDoItemViewController *source = [segue sourceViewController];
    ToDoItem *item = source.toDoItem;
    if (item != nil) {
        [self.toDoItems addObject:item];
        [self.tableView reloadData];
    }
}

- (void)viewDidLoad {
    [super viewDidLoad];
    self.toDoItems = [[NSMutableArray alloc] init];
    [self loadInitialData];
}

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

#pragma mark - Table view data source

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
    // Return the number of sections.
    return 1;
}

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:          
(NSInteger)section {
    // Return the number of rows in the section.
    return [self.toDoItems count];
}


- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath: (NSIndexPath *)indexPath {
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@"ListPrototypeCell" forIndexPath:indexPath];
    // Configure the cell...
    ToDoItem *toDoItem = [self.toDoItems objectAtIndex:indexPath.row];
    cell.textLabel.text = toDoItem.itemName;

    if (toDoItem.completed) {
        cell.accessoryType = UITableViewCellAccessoryCheckmark;
    } else {
        cell.accessoryType = UITableViewCellAccessoryNone;
    }
    return cell;
}

// Override to support editing the table view.
- (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath {
    if (editingStyle == UITableViewCellEditingStyleDelete) {

        // Delete the row from the data source
        [tableView deleteRowsAtIndexPaths:@[indexPath] withRowAnimation:UITableViewRowAnimationFade];
    } else if (editingStyle == UITableViewCellEditingStyleInsert) {
        // Create a new instance of the appropriate class, insert it into the array, and add a new row to the table view
    }   
}

Answer 1

调用deleteRowsAtIndexPaths后，它会刷新tableViews数据，然后调用cellForRowAtIndexPath。既然您没有更改数据，tableView中的任何内容都不会改变。

Answer 2

在tableView:(UITableView *)tableView commitEditingStyle: (UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath方法中，您只删除单元格。您还必须删除实际数据。

- (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath {
    if (editingStyle == UITableViewCellEditingStyleDelete) {

        // Delete data from array
        [self.toDoItems removeObjectAtIndex:indexPath.row];

        // Delete the row from the data source
        [tableView deleteRowsAtIndexPaths:@[indexPath] withRowAnimation:UITableViewRowAnimationFade];
    } else if (editingStyle == UITableViewCellEditingStyleInsert) {
        // Create a new instance of the appropriate class, insert it into the array, and add a new row to the table view
    }   
}

我无法从列表Xcode中删除项目

2 个答案: