NSDictionary对子对象进行谓词过滤 [英] NSDictionary Predicate filter on child objects

问题描述

我正在尝试过滤来自Facebook API的回复，JSON看起来像这样：

  {
 数据：[
 {
first_name：Joe，
last_name：bloggs，
uuid：123
} ，
 {
first_name：johnny，
last_name：appleseed，
uuid：321
} 
 ] 
} 
  

我将它加载到NSDictionary中，像 [[friendDictionary objectForKey：@data] allObjects]

我现在正在尝试根据 first_name 和 last_name 基于有人在文本字段中输入名称的时间。这是我所拥有的，但它的失败可怕：

  NSPredicate * filter = [NSPredicate predicateWithFormat：[NSString stringWithFormat：@ANY.first_name以[c]％@ OR ANY.last_name开头，以[c]％@开头，friendField.text，friendField.text]]; 
 NSLog（@％@，[[friendDictionary objectForKey：@data] allObjects] filteredArrayUsingPredicate：filter]）; 
  

非常感谢任何帮助，谢谢你们

• stringWithFormat 在 predicateWithFormat 中没有任何意义。


• 谓词中不需要ANY聚合，即使用与Core Data对象中的多对多关系。


• [friendDictionary objectForKey：@Data] 返回一个数组， allObjects 这里错了。


• 关键是数据，而不是数据。

这给出了

  NSPredicate * filter = [NSPredicate predicateWithFormat：@first_name startswith [c]％@ OR last_name以[c]％@开头，
 friendField.text，friendField.text]; 
 NSArray * filteredArray = [[friendDictionary objectForKey：@Data] filteredArrayUsingPredicate：filter]; 
  

I'm trying to filter a response from Facebook's API, the JSON looks like this:

{ 
 "Data": [
  {  
    "first_name" : "Joe",
    "last_name" : "bloggs",
    "uuid" : "123"
  },
  {  
    "first_name" : "johnny",
    "last_name" : "appleseed",
    "uuid" : "321"
  }
 ]
}

I load this into a NSDictionary, accessing it like [[friendDictionary objectForKey:@"data"] allObjects]

I'm now trying to filter based on the first_name and last_name based on when someone inputs a name into a textfield. Here's what I have but its failing horribly:

  NSPredicate *filter = [NSPredicate predicateWithFormat:[NSString stringWithFormat:@"ANY.first_name beginswith[c] %@ OR ANY.last_name beginswith[c] %@", friendField.text, friendField.text]];
  NSLog(@"%@", [[[friendDictionary objectForKey:@"data"] allObjects] filteredArrayUsingPredicate:filter]);

Any help is greatly appreciated, thanks guys

解决方案

You are thinking too complicated.

• stringWithFormat within predicateWithFormat makes no sense here.
• No need for the "ANY" aggregate in the predicate, that is used with to-many-relationships in Core Data objects.
• [friendDictionary objectForKey:@"Data"] returns an array, allObjects is wrong here.
• The key is "Data", not "data".

That gives

NSPredicate *filter = [NSPredicate predicateWithFormat:@"first_name beginswith[c] %@ OR last_name beginswith[c] %@",
    friendField.text, friendField.text];
NSArray *filteredArray = [[friendDictionary objectForKey:@"Data"] filteredArrayUsingPredicate:filter];

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