如何在Objective C中将两个数组的对象作为对象和键添加到第三个数组

Question

I am trying to add two arrays into the third array ie one array's objects are values to the third array and other array's objects are keys to the third array and I am getting the output as null , Is this a right way to do.

     NSArray *newcontactkeys,*newcontactvalues ;
     NSMutableArray *autoSyncDataArray;

    newcontactkeys=[self.resultDict objectForKey:@"keys"];
    newcontactvalues=[self.resultDict objectForKey:@"values"];
    [autoSyncDataArray setValue:[self.resultDict objectForKey:@"values"] 
    forKey:[self.resultDict objectForKey:@"Keys"]];

    NSLog(@"autosyncArray is %@",autoSyncDataArray);

Output: autosyncArray is (null)

Answer 1

You are using an array, which is an indexed collection, but talking about keys , dictionaries are keyed collections.

NSDictionary has a class method to directly create a dictionary from two arrays, use this and your code becomes, updating to modern Obj-C syntax:

NSArray *newContactKeys = self.resultDict[@"keys"];
NSArray *newContactValues = self.resultDict[@"values"];
NSDictionary *autoSyncDataDict = [NSDictionary dictionaryWithObjects:newContactValues
                                                             forKeys:newContactsKeys];

HTH

Answer 2

You're not initialising your array.

NSMutableArray *autoSynchDataArray = [NSMutableArray new]

Also use addObject instead of set value:

[autoSyncDataArray addObject:[self.resultDict objectForKey:@"values"]

Answer 3

You cannot join/Manipulate multiple Array of type NSArray. Create a NSMutableArray which allows reordering and manipulation of data in it. You can add any number of objects to it, rearrange it and delete it.

NSMutableArray *templateArray = [NSMutableArray new];

Answer 4

There are 2 issues:

1. Null issue: You are not initializing array. So you will have to use below statement:

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

2. Key/Value Pair: If you want to put keys and values in an array. It will not work like Dictionary. It will go into sequential form. If you are ok with sequential form then use:

   [autoSyncDataArray addObject:[self.resultDict objectForKey:@"keys"]]; [autoSyncDataArray addObject:[self.resultDict objectForKey:@"values"]];

otherwise use:

NSMutableDictionary *autoSyncDataDict = [[NSMutableDictionary alloc] init];
[autoSyncDataArray setValue:[self.resultDict objectForKey:@"values"] 
    forKey:[self.resultDict objectForKey:@"Keys"]];