如何从 NSMutableArray 中删除对象？

Posted 2023-02-27

【中文标题】如何从 NSMutableArray 中删除对象？

【英文标题】：How to delete objects from NSMutableArray?

【发布时间】：2012-08-26 10:36:20

【问题描述】：

由于某种原因，我的代码拒绝工作。我在方法- (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath 中遇到 sigbart 错误，我尝试从 tableView 和我的书签数组中删除对象？ （您可以在我的代码底部的 pragma 标记下找到方法 - 表格视图数据源）。

我是 Objective-C 和 iPhone 开发的新手，所以如果你知道什么可能导致这个错误，请尝试用我没有经验的假设来解释它。谢谢！

书签.h

#import <UIKit/UIKit.h>

#import "ShowTaskViewController.h"

#import "Bookmark.h"

@interface BookmarksViewController : UITableViewController  <UITableViewDelegate,UITableViewDataSource>

NSMutableArray *bookmarks;



@property (nonatomic, retain) NSMutableArray *bookmarks;
@end

书签.m

#import "BookmarksViewController.h"

@interface BookmarksViewController ()

@end

@implementation BookmarksViewController

@synthesize bookmarks;

- (id)initWithStyle:(UITableViewStyle)style

self = [super initWithStyle:style];
if (self) 
    // Custom initialization

return self;


- (void)viewDidLoad

[super viewDidLoad];
// Uncomment the following line to preserve selection between presentations.
// self.clearsSelectionOnViewWillAppear = NO;

// Uncomment the following line to display an Edit button in the navigation bar for this view controller.
// self.navigationItem.rightBarButtonItem = self.editButtonItem;


- (void)viewWillAppear:(BOOL)animated

NSUserDefaults *storage = [NSUserDefaults standardUserDefaults];
NSDictionary *storedBookmarks = [NSKeyedUnarchiver unarchiveObjectWithData:[storage objectForKey:@"bookmarks"]];

if (storedBookmarks == nil)

    storedBookmarks = [[NSDictionary alloc] init];


self.bookmarks = [storedBookmarks allValues];

[self.tableView reloadData];    
[super viewWillAppear:animated];


- (void)viewDidUnload

[super viewDidUnload];
// Release any retained subviews of the main view.
// e.g. self.myOutlet = nil;


- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation

return (interfaceOrientation == UIInterfaceOrientationPortrait);


#pragma mark - Table view data source

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView

return 1;


- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section

return [self.bookmarks count];


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

static NSString *CellIdentifier = @"BookmarkCell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];

if (cell == nil)

    cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];

Bookmark *item = [self.bookmarks objectAtIndex:indexPath.row];

NSArray *chunks = [item.name componentsSeparatedByString: @","];

NSString *name;
NSString *book;
NSString *chapter;

if ([chunks count] > 0)

    name = [chunks objectAtIndex:0];
    if ([chunks count] > 1)
    
        book = [chunks objectAtIndex:1];
        if ([chunks count] > 2)
        
            chapter = [chunks objectAtIndex:2];
        
    


cell.textLabel.text = name;
cell.detailTextLabel.text = book;

return cell;



- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender

if ([[segue identifier] isEqualToString:@"FromBookmarksToShowTaskSegue"])

    ShowTaskViewController *vc = [segue destinationViewController];

    Bookmark *item = [self.bookmarks objectAtIndex:[self.tableView indexPathForSelectedRow].row];

    vc.taskId =  item.id;



/*
// Override to support conditional editing of the table view.
- (BOOL)tableView:(UITableView *)tableView canEditRowAtIndexPath:(NSIndexPath *)indexPath

// Return NO if you do not want the specified item to be editable.
return YES;

*/


// 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:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade];

    [bookmarks removeObjectAtIndex:indexPath.row];

   
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
   

**编辑：在我改变位置后

[tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade]; [书签 removeObjectAtIndex:indexPath.row];

到

[bookmarks removeObjectAtIndex:indexPath.row];
[tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade];

我在另一个文件中收到一个新的 SIGBART 错误，代码如下：

#import <UIKit/UIKit.h>
#import "AppDelegate.h"

int main(int argc, char *argv[])

@autoreleasepool 
    return UIApplicationMain(argc, argv, nil, NSStringFromClass([AppDelegate class]));

有什么想法吗？

【问题讨论】：

如果您可以只显示您遇到问题的代码部分，这将是一个开始。很难通过一堵代码来找到您要修改数组的位置。

错误具体说明了什么？让我们看看数组的初始化。

【参考方案1】：

放线

[bookmarks removeObjectAtIndex:indexPath.row];

之前

[tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade];

编辑

我发现这一行还有一个问题：

self.bookmarks = [storedBookmarks allValues];

这不会保留数组的可变性。请更改它，以便您可以添加/删除书签对象：

self.bookmarks = [[storedBookmarks allValues] mutableCopy];

【讨论】：

嗯，发生了一些事情。但是现在我在我的 appdelegate.h 文件中获得了另一个 SIGBART。看看我的新帖

#import #import "AppDelegate.h" int main(int argc, char *argv[]) @autoreleasepool return UIApplicationMain(argc, argv, nil, NSStringFromClass ([AppDelegate 类]));