iOS 使用 NSDictionary 将数据加载到部分和行中

Posted 2023-03-04

【中文标题】iOS 使用 NSDictionary 将数据加载到部分和行中

【英文标题】：iOS Using NSDictionary to load data into section and rows

【发布时间】：2012-07-26 16:37:20

【问题描述】：

我希望在行中显示以日期作为部分标题和书名的表格部分。我完全不知道如何使用 NSDictionary 将数据加载到部分和行中。因此我的代码都搞砸了:(谁能提供一些帮助，以一些示例代码作为指导？我的 NSMutableArray 如下：

(
        
        BIBNo = 187882;
        date = "14/08/2012";
        itemSequence = 000010;
        name = "Increasing confidence / Philippa Davies.";
        noOfRenewal = 0;
        number = 000187907;
        status = "Normal Loan";
        time = "24:00";
        type = Loans;
    ,
        
        BIBNo = 291054;
        date = "14/08/2012";
        itemSequence = 000010;
        name = "iPhone application development for ios 4 / Duncan Campbell.";
        noOfRenewal = 2;
        number = 000291054;
        status = "Normal Loan";
        time = "24:00";
        type = Loans;
    ,
        
        BIBNo = 244441;
        date = "15/08/2012";
        itemSequence = 000010;
        name = "Coach : lessons on the game of life / Michael Lewis.";
        noOfRenewal = 1;
        number = 000244441;
        status = "Normal Loan";
        time = "24:00";
        type = Loans;
    ,
        
        BIBNo = 290408;
        date = "15/08/2012";
        itemSequence = 000010;
        name = "Sams teach yourself iPhone application development in 24 hours / John Ray.";
        noOfRenewal = 3;
        number = 000290408;
        status = "Normal Loan";
        time = "24:00";
        type = Loans;
    ,
        
        BIBNo = 161816;
        date = "16/08/2012";
        itemSequence = 000010;
        name = "Malaysian Q & As / compiled by Survey & Interview Department ; illustrations by Exodus.";
        noOfRenewal = 1;
        number = 000161817;
        status = "Normal Loan";
        time = "24:00";
        type = Loans;
    ,
        
        BIBNo = 187883;
        date = "16/08/2012";
        itemSequence = 000010;
        name = "Positive thinking / Susan Quilliam.";
        noOfRenewal = 3;
        number = 000187899;
        status = "Normal Loan";
        time = "24:00";
        type = Loans;
    
)

我实际上如何将对象重新添加到 NSDictionary 中，以便将具有相同日期的对象存储在一起以在该部分中显示为行？请给我一些建议谢谢！ T_T

【参考方案1】：

要处理您的数据，您需要执行类似的操作

NSMutableDictionary *dataSource = [[NSMutableDictionary alloc] init]; // This would need to be an ivar

for (NSDictionary *rawItem in rawItems) 
    NSString *date = [rawItem objectForKey:@"date"]; // Store in the dictionary using the data as the key

    NSMutableArray *section = [dataSource objectForKey:date]; // Grab the section that corresponds to the date

    if (!section)  // If there is no section then create one and add it to the dataSource
        section = [[NSMutableArray alloc] init];
        [dataSource setObject:section forKey:date];
    

    [section addObject:rawItem]; // add your object


self.dataSource = dataSource;

然后获取章节标题

NSArray *sections =[[self.dataSource allKeys] sortedArrayUsingSelector:@selector(caseInsensitiveCompare:)];
return [sections objectAtIndexPath:indexPath.section];

然后在一个section中获取一行

NSString *sectionTitle = // get the section title calling the above code
NSArray *items = [self.dataSource objectForKey:sectionTitle];

return [items objectAtIndex:indexPath.row];

【讨论】：

非常感谢！我使用您的代码作为指导并进行了一些编辑，它完全符合我的要求！！！非常感谢！！ :D

对不起，我有一个问题.. UI 结果很好，但是当我为书做续订按钮时，我注意到虽然书是按日期排序的，但按钮是被回收，我不知道如何为续订按钮设置标签。有什么建议吗？:)

你最好的选择是问另一个问题或环顾四周 - 我相信有很多与细胞重用有关的答案

【参考方案2】：

 - Dictionary of sections by date
  |
   --- array of row objects for the date1
  |    |
  |     --- row dictionary with the data to display
  |    |
  |     --- row dictionary with the data to display
  |    |
  |     --- row dictionary with the data to display
  |    |
  |     --- row dictionary with the data to display
  |
  |
  |
   --- array of row objects for the date2
  |    |
  |     --- row dictionary with the data to display
  |    |
  |     --- row dictionary with the data to display
  |    |
  |     --- row dictionary with the data to display
  |
  |
  |
  |
   --- array of row objects for the date3
       |
        --- row dictionary with the data to display
       |
        --- row dictionary with the data to display
       |
        --- row dictionary with the data to display
       |
        --- row dictionary with the data to display
       |
        --- row dictionary with the data to display

【讨论】：

谢谢！它帮助我更好地理解 NSDictionary 在做什么！非常感谢！ :)

【参考方案3】：

简而言之，您不能将对象重新添加到 NSDictionary。那是因为 NSDictionary 是不可变的。一旦它被创建，它的内容就不能被修改。你想要的是一个 NSMutableDictionary。

然后您可以使用 setObject:forKey: 方法。

[MyDict setObject:@"Normal Loan" forKey:@"status"];

https://developer.apple.com/library/mac/#documentation/Cocoa/Reference/Foundation/Classes/nsmutabledictionary_Class/Reference/Reference.html

【讨论】：

哦.. 我知道这就是 NSDictionary 和 NSMutableDictionary 之间的区别。想知道为什么.. 感谢您的贡献:)

【参考方案4】：

正如 A-Live 所说，您必须将数组排序到数组的可变字典中

以下代码应该可以工作，但未经测试

在 TableView 控制器.h

@interface MyController:UITableViewController
   NSMutableArray* dict;
   NSMutableArray* array;

在 MyController.m 中

-(void)initWithBooksArray:(NSArray*)bookArray //Or something similar

    self = [[super alloc] initWithStyle:UITableViewStylePlain];
    if(self)        
       dict = [[NSMutableDictionary alloc] init];
       array= [[NSMutableArray alloc] init];

       NSMutableArray* sectionArray;
       for(NSDictionary* bookDict in bookArray)

          date = [bookDict valueForKey:@"date"];
          sectionArray = [dict valueForKey:date];
          if(sectionArray)
             [sectionArray addObject:bookDict];
          else
             sectionArray = [[NSMutableArray arrayWithObject:bookDict];
             [dict addObject:sectionArray forKey:date];
          
       
       array = [[dict allKeys] sortedArrayUsingSelector:@selector(caseInsensitiveCompare:)];

    
    return self;


-(NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
   return [dict count];


-(NSInterger)tableView:(UITableView*)tableView numberOfRowsInSection:(NSInteger)section
   NSString* key = [array objectAtIndex:section];
   return [[dict objectForKey:key]count];

- (NSString *)tableView:(UITableView *)tableView titleForHeaderInSection:(NSInteger)section
   return [array objectAtIndex:section];


...

// I'll leave it to apple's documentation (or someone else) to fill in the blanks on how to create cells

【讨论】：

感谢您的帮助！ :) 但我使用了下面的答案。一样的感谢:)