Question

我正在使用一个像这样的结构的plist：plist，array，dict key string key string / dict，dict key string key string / dict，/ array，/ plist。

使用以下代码我想要将当前词典中的“完成”字符串值设置为“是”。

但是现在，代码用当前字典的字符串替换了整个字典数组（尽管如此，“Done”键值为“Yes”。）

我想要的正确代码是什么？

DetailViewController.m中的

：

-(IBAction)favoriteButtonPressed:(id)sender
{

NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSString *path = [documentsDirectory stringByAppendingPathComponent:@"Object.plist"];


[[detailsDataSource objectAtIndex: detailIndex] setValue:@"Yes" forKey:@"Done"];
[[detailsDataSource objectAtIndex: detailIndex] writeToFile:path atomically:YES];
}

如果重要的话，可以从TableViewController.m segue中获取detailsDataSource和detailIndex。

TableViewController.m segue part：

    detailViewController.detailsDataSource = [[NSArray alloc]initWithArray:objectsArray];
    detailViewController.detailIndex = selectedRowIndex.row;

DetailViewController viewDidLoad

if ([[[detailsDataSource objectAtIndex: detailIndex] valueForKey:@"Favorite"] isEqual:@"Yes"])  {

    [favoriteButton setImage:[UIImage imageNamed:@"favoritedItem.png"] forState:UIControlStateSelected | UIControlStateHighlighted];
 }


districtLabel.text = [[detailsDataSource objectAtIndex: detailIndex] valueForKey:@"District"];

detailsDataSource数组在detailViewController中使用如下所示我无法从数组更改为字典，在这种情况下必须创建一个可变副本。

Answer 1

setValue:forKey不是用于修改可变字典。您应该使用setObject:forKey。即，这个：

[[detailsDataSource objectAtIndex: detailIndex] setValue:@"Yes" forKey:@"Done"];

应该是：

[[detailsDataSource objectAtIndex: detailIndex] setObject:@"Yes" forKey:@"Done"];

如果这不能解决问题，请确保字典和数组都是可变的：

-(IBAction)favoriteButtonPressed:(id)sender {

    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *documentsDirectory = [paths objectAtIndex:0];
    NSString *path = [documentsDirectory stringByAppendingPathComponent:@"Object.plist"];

    NSMutableDictionary *mutDict = [NSMutableDictionary dictionaryWithDictionary:[detailsDataSource objectAtIndex:detailIndex]];
    [mutDict setObject:@"Yes" forKey:@"Done"];

    NSMutableArray *tmpMutArr = [NSMutableArray arrayWithArray:detailsDataSource];
    [tmpMutArr replaceObjectAtIndex:detailIndex withObject:[NSDictionary dictionaryWithDictionary:mutDict]];  // make dict immutable before replacing.  Casting it ( (NSDictionary *)mutDict ) works too.

    [detailsDataSource release], detailsDataSource = nil;
    detailsDataSource = [[NSArray alloc] initWithArray:tmpMutArr];

    [detailsDataSource writeToFile:path atomically:YES];
}

此外，您可以使用@"Yes"代替[NSNumber numberWithBool:YES]而不是[mutDict setObject:[NSNumber numberWithBool:YES] forKey:@"Done"]; @"Yes"
通常会使用districtLabel.text = [[detailsDataSource objectAtIndex: detailIndex] valueForKey:@"Yes"];更好的形式。

和

districtLabel.text = [[detailsDataSource objectAtIndex: detailIndex] objectForKey:@"Yes"];

应该是：

detailViewController.detailsDataSource = [[NSArray alloc] initWithArray:objectsArray];

还注意到可能内存泄漏：

{{1}}

确保在使用保留的属性设置器时自动释放。

Answer 2

[[detailsDataSource objectAtIndex: detailIndex] setObject:@"Yes" forKey:@"Done"];

在plist字典中写入字符串

2 个答案: