Objective c 按值（非键）按字母顺序对NSMutableDictionary排序

我有一个字典，它将学生id存储为键，将其显示名称存储为子字典“display”的键。字典看起来像这样：

id-1:
  display: mark
id-2:
  display: alexis
id-3:
  display: beth

PlistManager *pm = [[PlistManager alloc] init];
NSMutableDictionary *students = [pm getStudentsDict:ClassID];
NSMutableArray *sortedKeys = [[students allKeys] mutableCopy]; // remember to manually release the copies you create
[sortedKeys sortUsingComparator:^NSComparisonResult(id obj1, id obj2) {
    NSString *student1 = [students objectForKey:obj1];
    NSString *student2 = [students objectForKey:obj2];
    return [student1 compare:student2]; // this does a simple comparison, look at the NSString documentation for more options
}];
// at this point your sortedKeys variable contains the keys sorted by the name of the student they point to //
// if you want to create the other array you can do so like this:
NSArray *sortedStudents = [students objectsForKeys:sortedKeys notFoundMarker:[NSNull null]];

// you can also iterate through the students like so:
for (int i = 0; i < sortedKeys.count; ++i)
{
    NSString *key = sortedKeys[i];
    NSString *student = [students objectForKey:key];
}

// or access directly:
NSString *studentAtIndex3 = [students objectForKey:sortedKeys[3]];

// always remember to release or autorelease your copies //
[sortedkeys release];

我想把列表分成两个数组，一个用于键，一个用于值，看起来像这样

key   value
id-2  alexis
id-3  beth
id-1  mark

我目前有以下代码：

-(void)alphabetize {
    PlistManager *pm = [[PlistManager alloc] init];
    NSMutableDictionary *students = [pm getStudentsDict:ClassID];;
    NSMutableArray *keyArray = [[NSMutableArray alloc] init];
    NSMutableArray *valArray = [[NSMutableArray alloc] init];

    for (id key in students) {
        [keyArray addObject:key];
        [valArray addObject:[[students objectForKey:key] objectForKey:@"display"]];
    }

    NSSortDescriptor *alphaDescriptor = [[NSSortDescriptor alloc] initWithKey:@"DCFProgramName" ascending:YES selector:@selector(localizedCaseInsensitiveCompare:)];
    NSArray *sortedValues = [valArray sortedArrayUsingDescriptors:[NSMutableArray arrayWithObjects:alphaDescriptor, nil]];
    NSLog(@"%@", sortedValues);
}

但是它在创建sortedValues数组时抛出了一个错误

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如果有人能帮助我或者为我指出正确的方向，我将不胜感激。谢谢大家!

您必须根据它们在字典中链接的值对keys数组进行排序，然后创建第二个数组，尽管我觉得您实际上不需要第二个数组。实现所需功能的一种方法是使用

NSMutableArray

中的

sortUsingComparator:

方法，如下所示：

id-1:
  display: mark
id-2:
  display: alexis
id-3:
  display: beth

PlistManager *pm = [[PlistManager alloc] init];
NSMutableDictionary *students = [pm getStudentsDict:ClassID];
NSMutableArray *sortedKeys = [[students allKeys] mutableCopy]; // remember to manually release the copies you create
[sortedKeys sortUsingComparator:^NSComparisonResult(id obj1, id obj2) {
    NSString *student1 = [students objectForKey:obj1];
    NSString *student2 = [students objectForKey:obj2];
    return [student1 compare:student2]; // this does a simple comparison, look at the NSString documentation for more options
}];
// at this point your sortedKeys variable contains the keys sorted by the name of the student they point to //
// if you want to create the other array you can do so like this:
NSArray *sortedStudents = [students objectsForKeys:sortedKeys notFoundMarker:[NSNull null]];

// you can also iterate through the students like so:
for (int i = 0; i < sortedKeys.count; ++i)
{
    NSString *key = sortedKeys[i];
    NSString *student = [students objectForKey:key];
}

// or access directly:
NSString *studentAtIndex3 = [students objectForKey:sortedKeys[3]];

// always remember to release or autorelease your copies //
[sortedkeys release];

PlistManager*pm=[[PlistManager alloc]init]；
NSMutableDictionary*students=[pm GetStudentsDictionary:ClassID]；
NSMutableArray*sortedKeys=[[students allKeys]mutableCopy]；//请记住手动释放您创建的副本
[sortedKeys sortUsingComparator:^n比较结果（id obj1，id obj2）{
NSString*student1=[students objectForKey:obj1]；
NSString*student2=[students objectForKey:obj2]；
return[student1 compare:student2]；//这是一个简单的比较，有关更多选项，请参阅NSString文档
}];
//此时，sortedKeys变量包含按指向的学生姓名排序的键//
//如果要创建另一个阵列，可以这样做：
NSArray*sortedStudents=[学生对象标记：sortedKeys notFoundMarker:[NSNull]]；
//您也可以像这样反复浏览学生：
对于（int i=0；i

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希望有帮助。

我认为您不能将

NSSortDescriptor

与

NSString

数组一起使用。考虑使用<代码> SoTyDrayRaysUnter选择器<代码> > NSArray < /Cord>。如何排序这两个数组，以便键和对象在排序后匹配？错误是什么“扔”？好吧，你不能排序字典…您可以对allValues数组进行排序。。。这似乎很容易。。。但它不会改变字典。非常感谢，它很有魅力。我一个人永远也弄不明白。