nsdictionary 上的排序给出的结果与 nsarray 上的排序不同

Question

2 天前我问了如何按字符串对象中的第二个单词对元素进行排序的问题和

我得到了解决方案here

但现在我陷入了新问题

想想我有

nsarray with--> 名字和

nsdictionary 具有相同的 -->names(of nsarray) 作为值和电子邮件 ID 作为键

而我的 nsarray 包含

   "Test Teacher"

   "Anonymous"

   "Dok Teacher"

我的 nsdictionary 包含

   "Dok Teacher" --"a@g.com"

   "Anonymous" --  "b@g.com"

   "Test Teacher" --"c@g.com"

由于需要对这些数组和字典进行排序，因此我使用上面链接中给出的方法对它们进行了排序

但排序后我得到如下数据

排序后的nsarray第二个单词

   "Anonymous"

   "Test Teacher"

   "Dok Teacher"

排序后的字典第二个单词的值

   "Anonymous" --  "b@g.com"

   "Dok Teacher" --"a@g.com"

   "Test Teacher" --"c@g.com"

为什么使用相同的排序方法后，Dok Teacher 和 Test Teacher 在字典和 nsarray 中的不同位置。

以及如何以相同的顺序获取数组和字典。

nsarray 排序代码：

NSMutableArray *sortedArray = [NSMutableArray arrayWithArray:[teachersNames sortedArrayUsingComparator:^NSComparisonResult(id a, id b) {
        NSString *firstTeacher2ndWord = [[[((NSString*)a) componentsSeparatedByString:@" "] objectAtIndex:1] lowercaseString];
        NSString *secondTeacher2ndWord = [[[((NSString*)b) componentsSeparatedByString:@" "] objectAtIndex:1] lowercaseString];
        return [firstTeacher2ndWord compare:secondTeacher2ndWord];
    }]];

    NSLog(@"After %@",sortedArray);

    teachersSrc=[NSMutableArray arrayWithArray:sortedArray];

nsdictionary 排序代码

    myArray = [teachersList keysSortedByValueUsingComparator:^NSComparisonResult(id a, id b) {
        NSString *firstTeacher2ndWord = [[[((NSString*)a) componentsSeparatedByString:@" "] objectAtIndex:1] lowercaseString];
        NSString *secondTeacher2ndWord = [[[((NSString*)b) componentsSeparatedByString:@" "] objectAtIndex:1] lowercaseString];
        return [firstTeacher2ndWord compare:secondTeacher2ndWord];
    }];

    NSLog(@"After %@",myArray);

编辑：

我也尝试过对数组和字典的名字进行排序，然后对两者的姓氏进行排序，但它根本不起作用，

Answer 1

鉴于你有这个：

 NSArray *array = @[@"Test Teacher",@"Anonymous",@"Dok Teacher"];
 NSDictionary *dictionary = @{@"a@g.com":@"Dok Teacher",@"b@g.com":@"Anonymous",@"c@g.com":@"Test Teacher"};


//sort the array first
    NSArray *sortedArray = [array sortedArrayUsingComparator:^NSComparisonResult(id obj1, id obj2) {
    NSString *firstTeacher2ndWord  =[[(NSString *)obj1 componentsSeparatedByString:@" "]lastObject];
     NSString *secondTeacher2ndWord =[[(NSString *)obj2 componentsSeparatedByString:@" "]lastObject];


    if([firstTeacher2ndWord compare:secondTeacher2ndWord options:NSCaseInsensitiveSearch] == FALSE){ // means they are the same
        //compare full text
        firstTeacher2ndWord = (NSString *)obj1;
        secondTeacher2ndWord = (NSString *)obj2;
    }

    return [firstTeacher2ndWord compare:secondTeacher2ndWord options:NSCaseInsensitiveSearch];
}];

 NSLog(@"Sorted Array %@",sortedArray);

//sort the dictionary key using values
    NSArray *sortedDictionaryKey =[dictionary keysSortedByValueUsingComparator:^NSComparisonResult(id obj1, id obj2) {
      NSString *firstTeacher2ndWord  =[[(NSString *)obj1 componentsSeparatedByString:@" "]lastObject];
     NSString *secondTeacher2ndWord =[[(NSString *)obj2 componentsSeparatedByString:@" "]lastObject];


    if([firstTeacher2ndWord compare:secondTeacher2ndWord options:NSCaseInsensitiveSearch] == FALSE){ // means they are the same
        //compare full text
        firstTeacher2ndWord = (NSString *)obj1;
        secondTeacher2ndWord = (NSString *)obj2;
    }


    return [firstTeacher2ndWord compare:secondTeacher2ndWord options:NSCaseInsensitiveSearch]
}];

//get the values from the dictionary based on the sorted keys
 NSLog(@"Sorted Dictionary %@",[dictionary objectsForKeys:sortedDictionaryKey notFoundMarker:[NSNull null]]);

会给你这个输出：

//Sorted Array
Sorted Array(
Anonymous,
"Dok Teacher",
"Test Teacher"
)

//Sorted Dictionary
Sorted Dictionary(
    Anonymous,
    "Dok Teacher",
    "Test Teacher"
  )

Answer 2

首先Dictionary(teachersList)的value数组是未排序的，不知道里面的元素是怎么排列的。

第二个Dok Teacher和Test Teacher在第二个单词上是一样的，它们之间没有顺序，排序后的顺序取决于排序方式（稳定或不稳定）和原始数组的顺序.

如果值数组中的元素在teachersNames 中的顺序相同，则结果将相同。否则Dok Teacher 和Test Teacher 的顺序是不确定的。

注意：这里的值数组是teachersList.allValues

Answer 3

您的代码中的问题是第二个名称Teacher 包含两个单词。因此，当您在数组中进行相同的排序时。它将按字母顺序对名称进行排序。由于两个单词的第二个名称相同。所以它不会反映在输出中。但是，如果您更改顺序，那么您可以看到预期的输出。我已经实现了以下对数组进行排序的代码：-

当执行下面的代码时，你会得到输出：-

  NSArray *array1=@[@"Test Teacher",@"Anonymous",@"Dok Teacher"];
NSArray *sortedArray=[array1 sortedArrayUsingComparator:^NSComparisonResult(id obj1, id obj2) {
    return [obj1 compare:obj2 options:NSCaseInsensitiveSearch];
}];
NSLog(@"%@",sortedArray);

输出：-

 Anonymous,
 "Dok Teacher",
 "Test Teacher"