I want to use a multidimensional array. Can any one explain how to use that in an iPhone app? I'm new to Objective-C.
Here's what I'm trying to do:
I am spliting the main string on the basis of seprator and storing in an array.
replacing some content of this array's each elements with new substrings and new values are storing in an new array.
want to again split the each element of new array with a new seprator and want to store this new value in new array
assuming this will be eassy by using multidimention.
Thanks,
Aaryan
(the code I have so far)
- (void)viewDidLoad {
[super viewDidLoad];
NSMutableArray *arrSeprate = [[NSMutableArray alloc]init];
NSString *temp;
// it is a mysql query//
insertqry = #"INSERT INTO `userDecks` VALUES (1,2,618),(1,3,1471),(1,4,0),(1,5,0),(1,6,7784),(1,11,0),(1,12,469),(1,13,0),(1,16,0),(1,17,113),(1,18,0),(1,19,752),(1,20,60),(1,21,0),(1,30,0),(1,31,0),(1,32,159),(1,34,129),(1,46,143),(1,47,0),(1,53,105),(1,55,456),(1,65,0),(1,66,127),(1,67,131)";
//step-1 ----------begin--------
NSArray *listItems = [insertqry componentsSeparatedByString:#"),"];
//step-1 ----------end--------
int i=0;
//step-2 ----------begin--------
for (i = 1; i<[listItems count]; i++)
{
temp = [listItems objectAtIndex:i];
temp = [temp stringByReplacingOccurrencesOfString:#"(" withString:#"INSERT INTO `userInvitation` VALUES ("];
[arrSeprate addObject:temp];
}
//step-2 ----------end-------------
//step-3 ----------begin--------this will use the for loop to ll elemts of previous array
NSString *middleqry = [arrSeprate objectAtIndex:0];
NSArray *ItemsArray = [middleqry componentsSeparatedByString:#","];
NSLog(#"%#",ItemsArray);
}
Very easily, you can just add the itemsArray into the mutable array you created. This achieves the same as a multi-dimensional array. Alternatively, you can just use C multi-dimensional arrays with pointers.
Related
Ok so I populate the array like this:
NSMutableArray *participants;
for(int i = 0; i < sizeofpm; i++){
NSDictionary *pmpart_dict = [pm_participants objectAtIndex:i];
NSString *pmpart_email = [pmpart_dict objectForKey:#"email"];
NSString *pmpart_email_extra = [#"pm" stringByAppendingString:pmpart_email];
[participants setValue:pmpart_email forKey:pmpart_email_extra];
NSLog(#"%#", participants);
}
sizeofpm is 1. that is using count. to get the number of values in the array. How can i store values to that array? It doesnt seem to be working. Thanks!
you need to alloc it first. Try to change the first line to:
NSMutableArray* participants = [[NSMutableArray alloc] init];
also using setValue:forKey: wont work with an NSMutableArray as an array has no key.
Try using [participants addObject:pmpart_email];.
You don't create the array, you just declare it.
NSMutableArray *participants = [NSMutableArray array];
After that, setValue:forKey: will not add objects to an array. You need addObject::
[participants addObject:pmpart_email];
There is no key.
You are assigning a value to an NSMutableArray *participants like how you assign values to an NSDictionary object. To assign values to NSMutableArray you can call - (void)addObject:(id)anObject
So, I as some of the other answer have stated, you're missing your initializer for participants. However, judging by your use of setValue:forKey:, and how you appear to be structuring your data, you're not looking for NSMutableArray, but instead NSMutableDictionary. Arrays are simply lists, whereas dictionaries maintain key-value relationships, which you appear to be attempting to leverage.
Try this:
// some classes provide shorthand for `alloc/init`, such as `dictionary`
NSMutableDictionary *participants = [NSMutableDictionary dictionary];
for(int i = 0; i < sizeofpm; i++){
NSDictionary *pmpart_dict = [pm_participants objectAtIndex:i];
NSString *pmpart_email = [pmpart_dict objectForKey:#"email"];
NSString *pmpart_email_extra = [#"pm" stringByAppendingString:pmpart_email];
[participants setValue:pmpart_email forKey:pmpart_email_extra];
NSLog(#"%#", participants);
}
This will give you a dictionary in the form of
{
pmpart_email_extra: pmpart_email
}
I want to initialize an NSArray with numbers starting from 0,1,2,3... I know the count of the array. For example:
I have an array that needs to be initialized with 5 (count) as capacity. Now I want to initialize this array with 0,1,2,3,4 and I need to initialize it dynamically.
If the count of the array is 10, I need to initialize the array with 0,1,2,3,4,5,6,7,8,9 at respective indexes. The problem is that count of the array changes dynamically and I need to initialize it accordingly.
Can someone suggest me any idea on how to implement this?
NSMutableArray* arrOfObject = [[NSMutableArray alloc] init];
for(int i=0; i< [arr count]; i++)
{
arrOfObject addObject:[NSNumber numberWithInt:i];
}
Initialize a mutable array. Then add the numbers in a loop. Optionally initialize a new non-mutable array with your mutable one using arrayWithArray:.
int count = 5;//suppose this you want
NSMutableArray *array = [NSMutableArray array];
for(int i=0 ; i< count; i++) {
[array addObject:[NSNumber numberWithInt:i];
}
You just need to pass the count from where you want it, and it will dynamically generate your desired array.
Use NSMutableArray then just add as many as you need
int count = 10;
NSMutableArray *array = [[NSMutableArray alloc] init];
for (int i=0;i<count;i++) {
[array addObject:[NSNumber numberWithInt:i]];
}
I'm Trying here to add many arrays to one NSMutableArray
Actually am adding the same array with different values Many Times to one NSMutable Array
this the code:
NSMutableArray* wordsArray =[[NSMutableArray alloc] init ];
NSMutableArray* meaningsArray=[[NSMutableArray alloc]init];
NSMutableArray* wordsArrayTemp=[[NSMutableArray alloc]init];
NSMutableArray* meaningsArrayTemp=[[NSMutableArray alloc]init ];
NSMutableArray* allWords =[[NSMutableArray alloc]initWithCapacity:2];
NSMutableArray* allMeanings=[[NSMutableArray alloc]initWithCapacity:2];
for(int i=0;i<2;i++)
{
int wordsCounter=0;
[wordsArrayTemp removeAllObjects];
[meaningsArrayTemp removeAllObjects];
for(NSString *tmp in wordsArray)
{
NSString *meaning =[meaningsArray objectAtIndex:wordsCounter++];
subtmp= [ tmp substringWithRange:NSMakeRange(0,1)];
if([currentTable isEqualToString:#"arabicToEnglish"])
{
if([subtmp isEqualToString:[arabicLetters objectAtIndex:i]])
{
[wordsArrayTemp addObject:tmp];
[meaningsArrayTemp addObject:meaning];
}
}
else
if([subtmp isEqualToString:[englishLetters objectAtIndex:i]])
{
[wordsArrayTemp addObject:tmp];
[meaningsArrayTemp addObject:meaning];
}
}
[allWords insertObject:wordsArrayTemp atIndex:i];
// [allWords addObject: wordsArrayTemp];
[allMeanings addObject:meaningsArrayTemp];
NSLog(#"all words count%i",[[allWords objectAtIndex:i] count]);
}
The Problem :
The supposed behavior here is to have 2 different values in the allWords array .
But what Actually happens is that the 2 values filled with the same value with the last index Value.
I mean [allWords objectAtIndex:0] should have 2000 object and [allWords objectAtIndex:1] should have 3000 ,but what happens that they both have 3000 object !!
what am I missing here?!!
thnx
when you add an object to an array the object is not copied. You just save its memory address.
Basically you added the same temporary array to the parent array. And you did all your array manipulations to the same array.
Maybe this piece of unrolled loop code will make it a little bit clearer.
// create new array on a specific memory address. let's say this address is 0x01
NSMutableArray* wordsArrayTemp=[[NSMutableArray alloc]init];
// first iteration of your loop
// remove all objects from array at memory address 0x01
[wordsArrayTemp removeAllObjects];
// add objects to the array at address 0x01
[wordsArrayTemp addObject:tmp];
// insert array (still at address 0x01) to the parent array
[allWords insertObject:wordsArrayTemp atIndex:i];
// your allWords array now looks like this: {array#0x01}
// second iteration of your loop
// remove all objects from array at memory address 0x01!!! (still the same array as in the first iteration)
// since it's the same array all objects from the array at [allWords objectAtIndex:0] are removed too
[wordsArrayTemp removeAllObjects];
// add objects to the array at address 0x01
[wordsArrayTemp addObject:tmp];
// insert array (still at address 0x01) to the parent array
[allWords insertObject:wordsArrayTemp atIndex:i];
// your allWords array now looks like this {array#0x01, array#0x01}
the solution is pretty easy.
At the beginning of the for-loop instead of removing allObjects from the array create new arrays.
Just replace
[wordsArrayTemp removeAllObjects];
[meaningsArrayTemp removeAllObjects];
with
wordsArrayTemp = [NSMutableArray array];
meaningsArrayTemp = [NSMutableArray array];
Try to add one array simutaneously :
[[allWords array] addObject:wordsArray.array];
Hope it'll help
Try this:-
[allWords insertObject:[wordsArrayTemp copy] atIndex:i];
It should work.
is this the right way to do the same?
nsmutablearray *myarray1 //have some data in it
for (int i=0;i< [myarray1 count]; i++)
{
myArray2 = [NSMutableArray array];
[myArray2 addObject:i];
}
and how can i print this value of myarray2.
If you are trying to copy element of one array to other array then use following code:
NSMutableArray *secondArray = [NSMutableArray arrayWithArray:firstArray];
If you want to print element value then depending upon data stored in your array you can print element.
i.e if array contains string object then you can print like this:
for(int i=0;i<secondArray.count;i++)
{
NSLog(#"Element Value : %#",[secondArray objectAtIndex:i]);
}
if array contains any user define object then you can print like this:
for(int i=0;i<secondArray.count;i++)
{
UserDefineObject *obj = [secondArray objectAtIndex:i];
NSLog(#"Element Value with property value: %#",obj.property);
}
The easiest way to create a new array containing the same elements as the old array is to use NSCopying or NSMutableCopying.
NSArray* myArray2 = [myArray1 copy]; // myArray2 is an immutable array
NSMutableArray* myArray3 = [myArray1 mutableCopy]; // myArray3 is an mutable array
If you want to print the contents of an array for debugging purposes:
NSLog(#"myArray2 = %#", myArray2);
If you want prettier printing for a UI, you'll need to iterate through as others have suggested.
Just a conceptual description first:
I am reading input from a text file (a list of words) and putting these words into an NSArray using componentsSeparatedByString method. This works.
But I wanted to select the words randomly and then delete them from the array so as to ensure a different word each time. Of course, you cannot change the NSArray contents. So...
I copied the contents of the NSArray into an NSMutableArray and use IT for the selection source. This also works - 269 objects in each array.
To return a word from the NSMutableArray I use the following code:
note- the arrays are declared globally
as
arrMutTextWords = [[NSMutableArray alloc] init]; //stack for words
arrTextWords = [[NSArray alloc] init]; //permanent store for words
-(NSString*) getaTextWord
{
// if the mutable text word array is empty refill
if ([arrMutTextWords count] == 0){
for (int i = 0 ; i < [arrTextWords count]; i++)
[arrMutTextWords addObject:[arrTextWords objectAtIndex:i]];
}
int i = random() % [arrMutTextWords count];
NSString* ptrWord = [arrMutTextWords objectAtIndex:i];
[arrMutTextWords removeObjectAtIndex:i];
return ptrWord;
}
The program crashes during a call to the method above - here is the calling code:
arrTmp is declared globally arrTmp = [[NSArray alloc] init]; //tmp store for words
for (int i = 0 ; i < 4; i++) {
tmpWord = [self getaTextWord];
[arrTmp addObject:tmpWord];
[arrTmp addObject:tmpWord];
}
I'm thinking that somehow deleting strings from arrMutTextWords is invalidating the NSArray - but I can't think how this would occur.
One possible source for problems is your fetching AND removing the NSString object from your list. Removing it releases that NSString instance therefore devalidating your reference.
To be shure to retain a reference you should use this code sequence instead:
NSString * ptrWord = [[[arrMutTextWords objectAtIndex:i] retain] autorelease];
[arrMutTextWords removeObjectAtIndex:i];
return ptrWord;
By the way: You should use
NSMutableArray *mutableArray = [NSMutableArray arrayWithArray: array];
instead of copying all values by hand. While i do not know the implementation of NSMutableArray, i know from times long ago (NeXTstep), that there are several possible optimizations that may speed up basic NSArray operations.
And finally copying this way is much more concise.
Just ran this through XCode and got random words returned, however I skipped the whole for loop and used addObjectsFromArrayfrom NSMutableArray.
NSArray *randomArray = [[NSArray alloc] initWithObjects:#"Paul", #"George", #"John", nil];
NSMutableArray *muteArray = [[NSMutableArray alloc] init];
[muteArray addObjectsFromArray:randomArray];
int i = random() % [muteArray count];
NSString* ptrWord = [muteArray objectAtIndex:i];
[muteArray removeObjectAtIndex:i];
NSLog(#"ptrWord %#", ptrWord); //gave me a different name each time I ran the function.
Hope this clears some things up.