如何创建NSArray的NSArray

Question

我正试图将NSDictionary数组排序为基于NSDictionaryvalueForKey:首字母之一的字母化数组

实际上，我想要一个看起来有点像的东西

Array A // contains NSDictionaies with keyvalue MAF strings starting with A
 NSDictionary1
 NSDictionary2
 NSDictionary3
Array B // contains NSDictionaies with keyvalue MAF strings starting with B
 NSDictionary1
 NSDictionary2
 NSDictionary3
Array C // contains NSDictionaies with keyvalue MAF strings starting with C
 NSDictionary1
 NSDictionary2
 NSDictionary3
etc

所以我有一个字母数组，在每个字母数组中，我希望有一个NSDictionary值数组，keyValue MAFs的第一个字母应该匹配。

到目前为止，我有一系列字典，我已经像一样进行了排序

NSSortDescriptor *sortDescriptor;
        sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"MAF"
                                                      ascending:YES];
        NSArray *sortDescriptors = [NSArray arrayWithObject:sortDescriptor];
        sortedDictionaryArray = [arrayData sortedArrayUsingDescriptors:sortDescriptors]; // use this in cellforrow: and didselectrow:
        NSLog(@"%@", sortedDictionaryArray); // this gives me a sorted array of NSdictionaries based off their MAF keyvalue.

这就是NSDicitorial看起来像

HADM = 1;
ISLOT = 0;
ISVERT = 0;
MAF = "Yazot"; // keyvalue I am trying to work with.

然后我被卡住了，我不知道从这里该去哪里。如果有人能帮助我了解如何创建NSArray的NSArray NSDictionaries，那就太棒了！希望我已经解释了我试图正确地做什么，如果你需要更多的细节，请告诉我，我会提供。

Answer 1

此代码将首先使用分配给键@"MAF"的对象对字典数组进行排序。然后，它将创建一个新的Dictionary，为该字符串的每个第一个字母添加一个可变数组，并向其中添加对象

NSArray *array = @[@{@"MAF": @"Yazot"}, @{@"MAF": @"Lorem"},@{@"MAF": @"Ipsum"}, @{@"MAF": @"Laura"},@{@"MAF": @"Isit"}];
NSArray *sortedArray = [array sortedArrayUsingComparator:^NSComparisonResult(NSDictionary *obj1, NSDictionary *obj2) {
    return [obj1[@"MAF"] compare:obj2[@"MAF"]];
}];
NSMutableDictionary *dictionary = [NSMutableDictionary dictionary];
for (NSDictionary *dict in sortedArray) {
    NSString *firstLetter = [dict[@"MAF"] substringToIndex:1];
    if(![[dictionary allKeys] containsObject:firstLetter])
        dictionary[firstLetter] = [NSMutableArray array];
    [dictionary[firstLetter] addObject:dict];
}

---

如果需要不区分大小写的字符串处理，"L"one_answers"L"应该放在同一个数组中，执行

NSArray *array = @[@{@"MAF": @"Yazot"}, @{@"MAF": @"Lorem"},@{@"MAF": @"Ipsum"}, @{@"MAF": @"Laura"},@{@"MAF": @"Isit"}];
NSArray *sortedArray = [array sortedArrayUsingComparator:^NSComparisonResult(NSDictionary *obj1, NSDictionary *obj2) {
    return [obj1[@"MAF"] caseInsensitiveCompare:obj2[@"MAF"]];
}];
NSMutableDictionary *dictionary = [NSMutableDictionary dictionary];
for (NSDictionary *dict in sortedArray) {
    NSString *firstLetter = [dict[@"MAF"] substringToIndex:1];
    firstLetter = [firstLetter lowercaseString];
    if(![[dictionary allKeys] containsObject:firstLetter])
        dictionary[firstLetter] = [NSMutableArray array];
    [dictionary[firstLetter] addObject:dict];
}

---

中的字典结果

{
    i =     (
                {
            MAF = Ipsum;
        },
                {
            MAF = Isit;
        }
    );
    l =     (
                {
            MAF = Laura;
        },
                {
            MAF = Lorem;
        }
    );
    y =     (
                {
            MAF = Yazot;
        }
    );
}

Answer 2

我们可以从创建字典数组的字典开始。

NSMutableDictionary *dictsForFirstLetter = [[NSMutableDictionary alloc] init];
for (NSDictionary *dict in arrayData) {
    NSString *dictMAF = dict[@"MAF"];
    NSString *firstLetter = [[dictMAF substringToIndex:1] uppercaseString];
    NSMutableArray *dicts = dictsForFirstLetter[firstLetter];
    if (!dicts) {
        dicts = [[NSMutableArray alloc] init];
        dictsForFirstLetter[firstLetter] = dicts;
    }
    [dicts addObject:dict];
}

然后，您可以通过MAF值的第一个字母检索字典数组：

NSArray *dicts = dictsForFirstLetter[@"Y"];

---

要从中获得按字母顺序排列的数组，您可以对字典的键进行排序并对其进行枚举：

NSMutableArray *alphabetizedDicts = [[NSMutableArray alloc] init];
NSArray *firstLetters = [dictsForFirstLetter allKeys];
NSArray *sortedFirstLetters = [firstLetters sortedArrayUsingSelector:@selector(caseInsensitiveCompare:)];
for (NSString *firstLetter in sortedFirstLetters) {
    NSArray *dicts = dictsForFirstLetter[firstLetter];
    [alphabetizedDicts addObject:dicts];
}