Question

我试图根据值数组操作一个字典数组。

例如：

arrayOfDicts = 
(
        {
        caption = a;
        urlRep = "12";
    },
        {
        caption = b;
        urlRep = "34";
    },
        {
        caption = c;
        urlRep = "56";
    }
)

值数组：

urlReps = (12,56);

我想要实现的结果：

(
        {
        caption = a;
        urlRep = "12";
    },
        {
        caption = c;
        urlRep = "56";
    }
)

我现在根据数组添加的代码是：

NSMutableArray *arrayOfDicts;
NSMutableSet *urlReps;
[urlReps minusSet:[NSSet setWithArray:[arrayOfDicts valueForKey:@"urlRep"]]];

    // merge new dicts to the original array
    for (id urlRep in urlReps)
    {
        [arrayOfDicts addObject:@{ @"urlRep" : urlRep, @"caption" : @"" }];

    }

这增加了我的数组，如果数组中有更多的url，但是如果数组中的url与dict相比，我还需要删除

Answer 1

尝试使用NSPredicate来过滤数组：

NSArray *arrayOfDicts = .... //your existing data
NSArray *filteredURLParams = @[@"12",@"56"];

NSPredicate *urlPredicate = [NSPredicate predicateWithFormat:@"urlRep IN %@",filteredURLParams];    

NSArray *filteredDicts = [arrayOfDicts filteredArrayUsingPredicate:urlPredicate];

Answer 2

这是一些老式的，直截了当的，完全未经测试的代码： - ）

// Your data
NSMutableArray* arrayOfDicts = [...];
NSMutableSet* urlReps = [...];

// Will receive those dictionaries that have a matching urlRep 
NSMutableArray* filteredArrayOfDicts = [NSMutableArray arrayWithCapacity:0];

// Initially contains all urlReps, but we will successively
// eliminate those urlReps that we encountered
NSMutableSet* urlRepsNotSeen = [NSMutableSet setWithCapacity:0];
[urlRepsNotSeen addObjects:[urlReps allObjects]];

for (NSDictionary* dict in arrayOfDicts)
{
  NSString* urlRep = [dict valueForKey:@"urlRep"];
  if ([urlReps containsObject:urlRep])
  [
    [filteredArrayOfDicts addObject:dict];
    // Not sure what happens if urlRepsNotSeen does not contain the
    // urlRep (because we eliminated it earlier). If it crashes, add
    // this check:
    //   if ([urlRepsNotSeen containsObject:urlRep])
    [urlRepsNotSeen removeObject:urlRep];
}
arrayOfDicts = filteredArrayOfDicts;
for (NSString urlRepNotSeen in urlRepsNotSeen)
{
  [arrayOfDicts addObject:@{ @"urlRep" : urlRepNotSeen, @"caption" : @"" }];
}

如果在数组中找不到值，则从字典中删除对象

2 个答案: