如何创建NSArray of NSArray

Question

我正在尝试将NSDictionaries数组排序为基于NSDictionary valueForKey:第一个字母的按字母排列的数组。

实际上，我想要一些看起来像这样的东西

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

因此，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的第一个字母应该与之匹配。

到目前为止，我已经整理了一系列字典，如下所示

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NSDicitonary的样子

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

然后我被卡住了，我不知道从这里往哪里走。如果有人能帮助我理解如何创建一个NSArray of NSArrays NSDictionaries，那就太棒了！希望我已经解释了我想要做的正确的事情，如果你需要更多的细节，让我知道，我会提供。

Answer 1

这段代码将首先使用分配给键@"MAF"的对象对字典数组进行排序。而不是创建一个新字典，它将为该字符串的第一个字母添加一个可变数组，并将对象添加到其中。

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，则应将"L“和"l”放在同一个数组中，请执行以下操作

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];

}

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，您可以通过字典MAF值的第一个字母检索字典数组：

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

要从中获得一个按字母顺序排列的数组，您可以对字典的键进行排序并对它们进行枚举：

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];
}