How to append NSString wiht number? - objective-c

I'm new in Cocoa.
I have NSString - (e.g) MUSIC . I want to add some new NSString in Array,
And want to check something like this
if MUSIC already contained in Array, add Music_1 , after Music_2 and so on.
So I need to be able read that integer from NSString, and append it +1 .
Thanks

Use
NSString *newString = [myString stringByAppendingString:[NSString stringWithFormat:#"_%i", myInteger]];
if myString is "music", newString will be "music_1" or whatever myInteger is.
EDIT: I seem to have gotten the opposite meaning from the other answer provided. Can you maybe clarify what it is you are asking exactly?

Check it out:
NSMutableArray *array = [NSMutableArray arrayWithObjects:#"123", #"qqq", nil];
NSString *myString = #"MUSIC";
NSInteger counter = 0;
if ([array containsObject:myString]){
NSString *newString = [NSString stringWithFormat:#"%#_%d", myString, ++counter];
[array addObject:newString];
}
else
[array addObject:myString];

For checking duplicate element in Array you can use -containsObject: method.
[myArray containsObject:myobject];
If you have very big array keep an NSMutableSet alongside the array.Check the set for the existence of the item before adding to the array. If it's already in the set, don't add it. If not, add it to both.
If you want unique objects and don't care about insertion order, then don't use the array at all, just use the Set. NSMutableSet is a more efficient container.
For reading integer from NSString you can use intValue method.
[myString intValue];
For appending string with number you can use - (NSString *)stringByAppendingString:(NSString *)aString or - (NSString *)stringByAppendingFormat:(NSString *)format ... method.

Here's how you convert a string to an int
NSString *myStringContainingInt = #"5";
int myInt = [myStringContainingInt intValue];
myInt += 1;
// So on...

Related

removing null from arrays in Object-c

I have this snipped of code that results in an array with a whole bunch of "<null>" throughout and I need to figure out how to remove them. Obviously after smashing my head against the keyboard I'm asking for some help.
In my .h I have declared:
NSArray *sortedContacts;
NSArray *rawContacts;
And then in .m:
-(void) buildContacts {
ABAddressBook *addressBook = [ABAddressBook sharedAddressBook];
NSArray *contacts = [addressBook people];
rawContacts=contacts;
NSArray *firstNames = [rawContacts valueForKey:#"First"];
NSArray *lastNames = [rawContacts valueForKey:#"Last"];
NSArray *organization = [rawContacts valueForKey:#"Organization"];
NSMutableArray *fullNames = [NSMutableArray array];
for(int i = 0; i < [firstNames count]; i++)
{
NSString *fullName = [NSString stringWithFormat:#"%# %# %#",
[firstNames objectAtIndex:i],
[lastNames objectAtIndex:i],
[organization objectAtIndex:i]];
[fullNames addObject:fullName];
}
NSMutableArray *fullList = [[NSMutableArray alloc]initWithArray:fullNames];
[fullList removeObjectIdenticalTo: #"<null>"];
sortedContacts = [fullList sortedArrayUsingSelector:#selector(compare:)];
NSLog(#"%#",sortedContacts);
}
I've tried so many things that I just can't see the forest for the trees anymore.
The text <null> is how the singleton instance of NSNull describes itself. That is, it's what -[NSNull description] returns.
In turn, these NSNull objects are getting into your firstNames, lastNames, and organization arrays because that's what Key-Value Coding does when you call -valueForKey: on an array and some of the elements return nil when that message is forwarded on to them with the same key. That is, calling [rawContacts valueForKey:#"First"] causes NSArray to call [element valueForKey:#"First"] for each element in rawContacts and to put the result in the array it builds. But, since an array can't contain nil, if one of those elements returns nil from [element valueForKey:#"First"], an NSNull object is added in its place.
Then, you are formatting the string fullName from the corresponding elements of firstNames, lastNames, and organization. You need to check if any of those elements are NSNull using if ([value isKindOfClass:[NSNull class]]) and handling that. For instance, you might just skip that record. Or you might combine the available fields and leave out any unavailable ones.
In any case, none of the elements of fullList will be #"<null>" because formatting values into #"%# %# %#" can never result in that string. (It might be #"<null> <null> <null>" or something like that, but never just #"<null>".)
A quick look at your code suggests you cannot get any empty strings added to your array, (a) you add elements using:
[fullNames addObject:fullName];
and fullName is created using:
[NSString stringWithFormat:#"%# %# %#" ...
so even if the %#'s get replaced by nothing you'll still have 2 spaces...
Maybe this is why all the things you've tried fail, if you're looking for empty strings you won't find them.
(Addendum: Question now says you're looking for #"<null>", you won't get that either for the same reason - there is at least two spaces in your string.)
The simple answer to removing invalid entries in fullNames is not to add them in the first place. You are adding elements in a loop (for), and conditional logic (e.g. if) inside the loop to determine whether you have something valid to add - however you define "something valid" - and only add an item to fullNames if so.
HTH
I'm not really familiar with the AddressBook framework, however this might be what's causing the confusion:
The values you collect in your arrays firstNames, lastNames and organization can be of type NSString or NSNull. You have to do any null-checking within the for-loop, before the fullName-string is constructed.
Remove this useless line:
[fullList removeObjectIdenticalTo: #"<null>"];
And replace the contents of your for-loop with the following code:
for(int i = 0; i < [firstNames count]; i++)
{
NSString *firstName = [firstNames objectAtIndex:i];
NSString *lastName = [lastNames objectAtIndex:i];
NSString *org = [organization objectAtIndex:i];
NSMutableArray *namesArray = [NSMutableArray array];
if ([firstName isKindOfClass:[NSString class]])
[namesArray addObject:firstName];
if ([lastName isKindOfClass:[NSString class]])
[namesArray addObject:lastName];
if ([org isKindOfClass:[NSString class]])
[namesArray addObject:org];
if (namesArray.count > 0)
[fullNames addObject:[namesArray componentsJoinedByString:#" "]];
}

How to add negative float in NSMutableArray?

Ok. i don't see ways to done it. But maybe some one knows?
I don't need use NSString to put it in array, because it makes huge memory usage.
NSMutableArray *array = #[#(-16.f)].mutableCopy;
for (NSNumber *number in array) {
NSLog(#"%f", number.floatValue);
}
first you need to convert yourfloat value toNSNumber using #(floatValue) .
NSMutableArray *arr = [[NSMutableArray alloc]init]; // here you can add value using initWithObject method.
[arr addObject:#(-16)]; // here you can add your float value using #(float value).
NSLog(#" array = %#",arr);
When you retrive value from array .
float yourValue = [[arr objectAtIndex:(your index)] floatValue];
hope it help you .

discussing functionality of id's stringValue function?

I got a NSMutableArray object with int values
and I can get a certain value via :
int *v0=[[[arrayObj objectAtIndex:0] intValue];
there is no problem.
But
I got a NSMutableArray object with NSString values
and I cannot get a certain value via :
NSString *v0=[[[arrayObj objectAtIndex:0] stringValue];
//raises error
I want to learn and understand exactly what stringValue for... and why this error occurs ?
NSString *v0=[arrayObj objectAtIndex:0];
works as expected.I asusme its some kind of pointer with null terminated so it can leech value.
Im not sure this line is also unicode/encoded string safe code.
in conclusion:
want to know the purpose of stringValue with some lines o code snippets
I got a NSMutableArray object with int values
That's not possible, Cocoa arrays always contain objects. You probably have an array of NSNumber objects that wrap the integers, like:
NSArray *arrayOfNumbers = #[#1, #2, #3];
NSNumber objects have an intValue method, so this works:
int value = [arrayOfNumbers[0] intValue];
On the other hand when you have an array of strings ...
NSArray *arrayOfStrings = #[#"1", #"2", #"3"];
... you want to access individual elements directly, without converting the string object to something else:
NSString *element = arrayOfStrings[0];
NSString objects do not understand the stringValue method:
[arrayOfStrings[0] stringValue]; // crash: does not recognize selector
Back at the beginning, our NSNumber objects from the first array do understand stringValue. You can use it to convert the number to a string:
NSString *intString = [arrayOfNumbers[0] stringValue];
To make the confusion perfect, NSString also understand the intValue message:
int value = [arrayOfStrings[0] intValue];
Here intValue means to try to convert the string to a plain C int value.
The error you will be getting (but failing to post with your question) will be Unknown selector sent to instance and this is because NSString doesn't have a stringValue method.
The approach you suggest is correct:
NSString *v0 = [arrayObj objectAtIndex:0];
EDIT (prompted by #Answerbot's answer):
The reason you are confused is that [NSString intValue] is used to convert the string value to an integer, as long as the string represents an integer (i.e. #"123"). However you don't need this for string as the object is already a string. It's therefore not provided.

Converting NSString to key value pair

I have a response from server which is NSString and looks like this
resp=handshake&clientid=47D3B27C048031D1&success=true&version=1.0
I want to convert it to key value pair , something like dictionary or in an array .
I couldn't find any useful built-in function for decoding the NSString to NSdictionary and replacing the & with space didn't solve my problem , can anyone give me any idea or is there any function for this problem ?
This should work (off the top of my head):
NSMutableDictionary *pairs = [NSMutableDictionary dictionary];
for (NSString *pairString in [str componentsSeparatedByString:#"&"]) {
NSArray *pair = [pairString componentsSeparatedByString:#"="];
if ([pair count] != 2)
continue;
[pairs setObject:[pair objectAtIndex:1] forKey:[pair objectAtIndex:0]];
}
or you could use an NSScanner, though for something as short as a query string the extra couple of arrays won't make a performance difference.

iPhone - Splitting an NSString into char NSStrings

I've got a 2d NSArray of {{"foo","food only only"}, {"bar","babies are rad"} ... } and I need to end up with 2 NSArrays: one of characters and one of the corresponding words. So #"f", #"o",#"b",#"a",#"r" and #"food",#"only",#"babies",#"are",#"rad" would be my two NSArray's of NSStrings.
So first, how do I get #"f",#"o",#"o" from #"foo"
And second how can I only keep the uniques? I'm guessing NSDictionary and only add if key is not there giving me #"f":#"food" #"o":#"only" then use getObjects:andKeys: to get two C arrays which I'll convert to NSArrays..
Based on the below answer I went with the following. I didn't actually use the NSMutableDict, I just added my letters to it to get the uniqueness check before creating my 2 output arrays:
unichar ch = [[arr objectAtIndex:0] characterAtIndex:i];
NSString *s = [NSString stringWithCharacters: &ch length: 1];
if (![dict objectForKey:s]) {
}
getCharacters will get you started with an array of characters: http://developer.apple.com/library/mac/#documentation/Cocoa/Reference/Foundation/Classes/NSString_Class/Reference/NSString.html#//apple_ref/occ/instm/NSString/getCharacters:
You could cycle through and check for uniques after
If you want the individual characters of a string, try -characterAtIndex:. That will get you them as the unichar primitive type, which you can then wrap in NSString like so:
unichar ch = ...;
NSString *chString = [NSString stringWithCharacters: &ch length: 1];
To keep uniques, you can store objects in an NSMutableSet, though it will not preserve the order in which objects are added to it.