what i am doing is sorting the labels for that i am assigning the string array to temporary string variable as follows:
NSString *tmp = [labels objectAtIndex:j-1];
labels[j-1]=labels[j];
labels[j] = tm;
but it shows error at last line that is incomplete types in assignment
how can i solve this?
thank you
Labels is not a C array, it's and Objective-C array, so you need to do
NSMutableArray *labels2 = [[NSMutableArray alloc] initWithArray:labels];
NSString *tmp = [labels objectAtIndex:j-1];
[labels2 insertObject:[labels objectAtIndex:j] atIndex:j-1];
[labels2 insertObject:tm atIndex:j];
Related
I'm using this code with ARC:
NSMutableDictionary *datesDict = [[NSMutableDictionary alloc]init];
NSMutableArray *datesArray = [[NSMutableArray alloc]init];
for (NSString *key in programsArray) {
datesArray = [_onDemandDictionary objectForKey:key];
NSMutableArray *newDates = [[NSMutableArray alloc]init];
int count;
for (count = 0; count <datesArray.count; count++) {
NSMutableDictionary *programsDict = [[NSMutableDictionary alloc]init];
programsDict = [datesArray objectAtIndex:count];
[newDates addObject:[programsDict objectForKey:#"date"]];
}
[datesDict setObject:newDates forKey:key];
}
But when I run the analyzer tool I'm getting value stored to (datesArray and programsDict) during its initialization is never read on lines:
NSMutableArray *datesArray = [[NSMutableArray alloc]init];
programsDict = [datesArray objectAtIndex:count];
Why is this happening how do I get hid of the warning?
Thank you!
The issue is you create a new NSMutableArray and assign it to datesArray at the beginning
NSMutableArray *datesArray = [[NSMutableArray alloc]init];
Then almost immediately after you assign a completely different value to datesArray with
datesArray = [_onDemandDictionary objectForKey:key];
I would just start with
NSMutableArray *datesArray = nil;
It's the same concept for programsDict.
On line 2, you create a new array datesArray.
Then, on line 6 (first line of the for loop), you set a new value to datesArray.
The compiler is just warning you that the line 2 has no effect, and that the code is bugged (in the sense it does not do what you expect).
True, the programsArray could be an empty array, and in this case you want datesArray to just be initialized to use it after the snippet you showed us, but it would be better to make this explicit.
For programsDict, it is even easier: you initialize it with ... alloc] init] then set it to an object of datesArray, making the first operation useless.
You are not using datesArray in your loop, you are simply assigning it values, So either take it nil array like
NSMutableArray* datesArray = nil;
or like
NSMutableArray *datesArray;
to remove waring .
i have to create an 2images and 3 labels by using code (cgrectmake)and i am having X location, y location, width and height all are stored in arrays(which i have retrieved from the web services)how can i create the image and labels can any one help me
You can join the elements of an array together with the NSString componentsJoinedByString class method:
NSString myString = [myNSArray componentsJoinedByString:#"x"];
where x is the characters you'd like to appear between each array element.
Edited to add
So in your newly-added code if these are the label values:
lbl = #"zero"
lbl1 = #"one"
lbl2 = #"two"
and you want to join them together with a space character then if you did this:
NSString *temp = [labelArray componentsJoinedByString:#" "];
NSLog(#"temp = %#", temp);
then this is what would be logged:
zero one two
Edited to further add
If you are instead trying to join the label values together to make xml elements then you might do something like this:
NSString *joinedElements = [labelArray componentsJoinedByString:#"</label><label>"];
NSString *temp = [NSString stringWithFormat:#"<label>%#</label>", joinedElements];
NSLog(#"temp = %#", temp);
then this is what would be logged:
<label>zero</label><label>one</label><label>two</label>
may be this is usefull to you.
NSString *str;
str = [arrayName objectAtIndex:i(Index NO)];
OK by this easily you can access object from the array. any type of object u can fetch this way only reception object type are change in left side.
Best of Luck.
Most objects have a -description method which returns a string representation of the object:
- (NSString *)description;
For example:
NSArray *array = [NSArray arrayWithObjects:#"The", #"quick", #"brown", #"fox", nil];
NSLog(#"%#", array); // prints the contents of the array out to the console.
NSString *arrayDescription = [array description]; // a string
It would help to know what you want to do with the string (how will you use the string). Also, what kind of objects do you have in the array?
In that case, Matthew's answer is one possibility. Another might be to use an NSMutableString and append the individual items, if you need control over how the string is created:
NSMutableString *string = [NSMutableString string];
if ([array count] >= 3) {
[string appendString:[array objectAtIndex:0]];
[string appendFormat:#"blah some filler text %#", [array objectAtIndex:1]];
[string appendString:[array objectAtIndex:2]];
}
i have an array of 5 objects.
i want to assign object which is at index 1, to an NSSTRING.
nsstring *abc = [array objectAtindex:1];
i know this is wrong syntax, this is returning object , something like this.
how can i get value which is at index 1 and assign it to an string?
regards
Erm.. this is the correct syntax :)
Apart the name of the string class:
NSString *abc = [array objectAtIndex:1];
mind that this won't create a copy of the string, if you need to copy it use
NSString *abc = [NSString stringWithString:[array objectAtIndex:1]];
As Eiko notes you can directly copy the string object if you need to:
NSString *abc = [[array objectAtIndex:1] copy];
Arrays are zero based in Objective-C land. So...
NSArray *array = [NSArray arrayWithObjects:#"one", #"two", nil];
NSString *abc = [array objectAtIndex:1];
Would return the second object in the array. Zero would return the first.
I'm trying to include the elements of an array in the NSString that's returned by the -description method in my class. No clue how to do this in Objective-C...in Java there's string concatenation or StringBuilder, what's the equivalent in Obj-C?
TIA..
Just use NSArray's componentsJoinedByString: method with whatever you want between them as the argument.
NSString *elementsSquishedTogether = [myArray componentsJoinedByString:#""];
NSString *connectedByACommaAndSpace = [myArray componentsJoinedByString:#", "];
If you have a C array, you can turn it into an NSArray with NSArray *converted = [NSArray arrayWithObjects:yourCArray count:yourArrayCount].
The title of your thread talks about C arrays, so here's a modification of jsumners' answer that will deal wiith C arrays.
myArray is assumed to be an ivar declared thusly:
int* myArray;
storage for myArray is assumed to be malloc'd at some point and the size of it is in an ivar declared:
int myArraySize;
The code for description goes something like
- (NSString *)description
{
NSMutableString *returnString = [[[NSMutableString alloc] init] autorelease];
for (int i = 0 ; i < myArraySize ; i++)
{
if (i > 0)
{
[returnString appendString: #", "];
}
[returnString appendFormat: #"%d", myArray[i]];
}
return [NSString stringWithFormat: #"[%#]", returnString];
}
There are variations. The above version formats the string with bracket delimiters and commas between elements. Also, it returns an NSString instead of an NSMutableString which is not a big deal, but I feel that if you say you are returning an immutable object, you probably should.
The following could should "build" a string representation of your array. Notice that it is using the -description method of the objects in the array. If you want something different you will have to make the necessary change.
- (NSString *)description: (id) myArr {
NSMutableString *returnString = [[[NSMutableString alloc] init] autorelease];
for (int i = 0, j = [myaArr count]; i < j; i++) {
[returnString appendString: [[myArr objectAtIndex: i] description]];
}
return [NSString stringWithString: returnString];
}
Edit:
As JeremyP said, I answered this using Objective-C arrays. I guess I just forgot the question when I started writing my code. I'm going to leave my answer as an alternative way to do it, though. I've also fixed the return string type from a mutable string to an immutable string (as it should be).
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.