NSDictionary到NSArray？

Question

i have a NSDictionary which looks like:

{
"Item1" = 2.4;
"Item2" = 5.5;
"Item3" = 15.6;
}

To use this NSDictionary Items in a Table View i have to transfer it to a NSArray , am i right?

So i try:

NSDictionary *dict = [myDict objectForKey:@"items"];

for (id item in dict) {
    [_myArray addObject:[dict objectForKey:item]];
}

But _myArray keeps empty? What am i doing wrong?

Answer 1

NSArray * values = [dictionary allValues];

Answer 2

NSArray *keys = [dictionary allKeys];
NSArray *values = [dictionary allValues];

Answer 3

Leaving aside the technical issues with the code you posted, you asked this:

To use this Dictionary Items in a Table View i have to transfer it to a NSArray, am i right?

The answer to which is: not necessarily. There's nothing intrinsic to the machinery of UITableView , UITableViewDataSource , or UITableViewDelegate that means that your data has to be in an array. You will need to implement various methods to tell the system how many rows are in your table, and what data appears in each row. Many people find it much more natural and efficient to answer those questions with an ordered data structure like an array. But there's no requirement that you do so. If you can write the code to implement those methods with the dictionary you started with, feel free!

Answer 4

您可以创建字典中所有对象的数组，然后将其用作TableView的数据源。

NSArray *aValuesArray = [yourDict allValues];

Answer 5

Code Snippet1:

NSMutableArray *array = [[NSMutableArray alloc] init];
NSArray * values = [dictionary allValues];
[array addObject:values];

Code Snippet2: If you want to add further

[array addObject:value1];
[array addObject:value2];
[array addObject:value3];

And so on

Also you can store key values of dictionary to array

NSArray *keys = [dictionary allKeys];

Answer 6

There are a few things that could be happening here.

Is the dictionary you have listed the myDict ? If so, then you don't have an object with a key of @"items" , and the dict variable will be nil. You need to iterate through myDict directly.

Another thing to check is if _myArray is a valid instance of an NSMutableArray. If it's nil, the addObject: method will silently fail.

And a final thing to check is that the objects inside your dictionary are properly encased in NSNumbers (or some other non-primitive type).

Answer 7

您只需要初始化NSMutableArray

NSMutableArray  *myArray = [[NSMutableArray alloc] init];

Answer 8

This code is actually used to add values to the dictionary and through the data to an Array According to the Key .

NSMutableArray *arr = [[NSMutableArray alloc]init];
NSDictionary *dicto = [[NSMutableDictionary alloc]initWithObjectsAndKeys:@"Hello",@"StackOverFlow",@"Key1",@"StackExchange",@"Key2", nil];
NSLog(@"The dictonary is = %@", dicto);
arr = [dicto valueForKey:@"Key1"];
NSLog(@"The array is = %@", arr);

Answer 9

+ (NSArray *)getArrayListFromDictionary:(NSDictionary *)dictMain paramName:(NSString *)paramName
{
    if([dictMain isKindOfClass:[NSDictionary class]])
    {
        if ([dictMain objectForKey:paramName])
        {
            if ([[dictMain objectForKey:paramName] isKindOfClass:[NSArray class]])
            {
                NSArray *dataArray = [dictMain objectForKey:paramName];

                return dataArray;
            }
        }
    }
    return [[NSArray alloc] init];
}

Hope this helps!

Answer 10

To get all objects in a dictionary, you can also use enumerateKeysAndObjectsUsingBlock: like so:

NSMutableArray *yourArray = [NSMutableArray arrayWithCapacity:6];
[yourDict enumerateKeysAndObjectsUsingBlock:^(id key, id obj, BOOL *stop) {
    [yourArray addObject:obj];
}];

Answer 11

In Swift 4:

let dict = ["Item1":2.4, "Item2": 5.4, "Item3" : 6.5]

let array = Array(dict.values)