I have a question about the objective-C. I use the following code to add a contains from an array to another array. However, the second array is null. Can anyone help me? Thank you.
titleArray = [[csvDataArrayString objectAtIndex:0] componentsSeparatedByString:#","];
NSString *title;
dataTitleArray = [[NSMutableArray alloc] init]; // after add this statement it's ok
for(int i=0; i<[tTitleArray count]; i++)
{
title = [csvPersonalTitleArray objectAtIndex:i];
[dataTitleArray addObject:title]; // the dataTitleArray is null
}
You haven't shown that you're actually allocating dataTitleArray anywhere. Are you? It's not clear what you're trying to do.
Related
I have two codes. Not working is the following:
NSMutableArray *tmpArray = [[NSMutableArray alloc] init];
for (int i=0; i<[dataSetArray count]; i++) {
tmpArray = (NSMutableArray *) [dataSetArray objectAtIndex:i];
// OR use: tmpArray = dataSetArray[i]
... doing stuff
[tmpArray replaceObjectAtIndex:0 withObject:tmpStr];
}
While this works:
for (int i=0; i<[dataSetArray count]; i++) {
NSMutableArray *tmpArray = [[NSMutableArray alloc] initWithArray:[dataSetArray objectAtIndex:i]];
... doing stuff
[tmpArray replaceObjectAtIndex:0 withObject:tmpStr];
}
Two questions:
The first code doesn't yield an NSMutableArray. Why? I declare it
above.
Is there a better way to obtain the same result. I just
dislike defining variables in a loop. This makes the code
unreadable.
--- edit:
Here the full code:
Datatypes are:
dataSetArray: NSMutableArray. However, its contents (i.e. dataSetArray[i]) are NSArrays (I read them into the program from an excel file).
NSString *tmpStr = [[NSString alloc] init];
for (int i=0; i<[dataSetArray count]; i++) {
NSMutableArray *tmpArray = [[NSMutableArray alloc] initWithArray:[dataSetArray objectAtIndex:i]];
for (int j=0; j<[tmpArray count]; j++) {
if ( [dataSetArray[0][j] isEqualToString:#"Number"] ) {continue;}
tmpStr = (NSString *) [tmpArray objectAtIndex:j];
// replace single backslash by double-backslash:
tmpStr = [tmpStr stringByReplacingOccurrencesOfString:#"\\" withString:#"\\\\"];
// replace first dollar sign by "<p>\\[" and second by "\\]</p>"
// Use a methode defined in the NSString+Extension
tmpStr = [tmpStr replaceTexFormulaSigns:tmpStr];
//NSLog(#"j=%d", j);
//NSLog(#"tmpArray is of type: %#", [tmpArray class]);
//NSLog(#" tmpStr is of type: %#", [tmpStr class]);
[tmpArray replaceObjectAtIndex:j withObject:tmpStr];
}
[dataSetArray replaceObjectAtIndex:i withObject:tmpArray];
}
So even if I use your suggestion, I am still facing the same problem with the inner array.
The first code doesn't yield a NSMutableArray. Why? I declare it above.
The declaration of the reference variable tmpArray does not change the type of the referred object. It is still an (immutable) array.
The creation of the mutable array at the very beginning of the first snippet is without any meaning, because the reference to it is overridden.
Is there a better way to obtain the same result. I just dislike defining variables in a loop. This makes the code unreadable.
Yes. The second example works in a way, but do something completely different. (It always creates a new array with a single item in it. No, that's not true. It shouldn't compile at all.)
You should do:
NSMutableArray *tmpArray = [dataSetArray mutableCopy];
for (int i=0; i<[dataSetArray count]; i++)
{
…
[tmpArray replaceObjectAtIndex:i withObject:tmpStr];
}
You should really get some additional knowledge about objects and object references.
i'm programming in Obj-c with xcode4.1, i have an array with numbers in it, and i want to visualize all of them in a label...can anyone help me around this please?
thanks!
this is the code:
combinedString=[[NSMutableArray alloc] init];
NSString *finalStringLabel=#"";
for (i=0; i<=textLength; i++) {
//character coding
char myChar = [myString characterAtIndex:i];
NSString *myCharS=[NSString stringWithFormat:#"%c", myChar];
int asciiCode=[myCharS characterAtIndex:0];
NSString *asciiS=[NSString stringWithFormat:#"%i", asciiCode];
[combinedString addObject:asciiS];
}
finalStringLabel=[NSString stringWithFormat:#"", [combinedString componentsJoinedByString:#"."]];
myLabel.text=finalStringLabel;
[combinedString release];
}
You can use this
NSArray *yourArray;
NSString *createdString = [yourArray componentsJoinedByString:#" "];
myLabel.text = createdString;
As your array is combinedString,
combinedString=[[NSMutableArray alloc] init];
looks like you are providing values after this line or this is not a property (this is a local as you are releasing it later), and your code in not complete.
Anyways,
You don't need to create an empty string and then assign new object to it, need to do as :
myLabel.text=[combinedString componentsJoinedByString:#"."];
[combinedString release];
}
I'm trying to add objects to NSMutableArray (categoriasArray), but its not done by the iterator:
#synthesize categoriasArray;
for (int i = 0; i < [categories count]; i++) {
categoria *cat = [[categoria alloc] initWithDictionary:[categories objectAtIndex:i]];
[self.categoriasArray addObject:cat];
cat=nil;
}
After the for iterator, categoriasArray has 0 objects.
Many thanks
Check that the array is not nil before the loop starts:
NSLog(#"%#", self.categoriasArray); // This will output null
for (int i = 0; i < [categories count]; i++) {
// ...
}
What you should understand is that synthesizing the property categoriasArray doesn't initialize it, it just generates the setter and the getter methods. So, to solve your problem, initialize the array before the loop, (or in the init method of your class):
self.categoriasArray = [[NSMutableArray alloc] init];
The other possibility is that categories is itself nil or doesn't contain any items. To check that, add NSLogs before the loop:
NSLog(#"%#", self.categoriasArray);
NSLog(#"%#", categories);
NSLog(#"%d", [categories count]);
for (int i = 0; i < [categories count]; i++) {
// ...
}
try this
for(categoria *cat in categoria){
[self.categoriasArray addObject:cat];
// check you go here or not
}
I would advise getting in the habit of initializing your arrays with autorelease formatting such as the following.This is not only less to type but also good practice for mem management purposes. Of course if you are using ARC then both will work. This goes the same for NSString and many others (i.e. self.categoriasString = [NSMutableString string];)
self.categoriasArray = [NSMutableArray array];
Afterword you can add objects to that array by calling [self.categoriasArray addObject:cat];
I'm doing this:
for(int i=0;i>count;i++)
{
NSArray *temp=[[NSArray alloc]initWIthObjects]i,nil];
NSLog(#"%i",temp);
}
It returns to me 0,1,2,3....counting one by one, but I want an array with appending these values {0,1,2,3,4,5...}.
This is not a big deal, but I'm unable to find it. I am new to iPhone.
NSMutableArray *myArray = [NSMutableArray array];
for(int i = 0; i < 10; i++) {
[myArray addObject:#(i)];
}
NSLog(#"myArray:\n%#", myArray);
This code is not doing what you want it to do for several reasons:
NSArray is not a "mutable" class, meaning it's not designed to be modified after it's created. The mutable version is NSMutableArray, which will allow you to append values.
You can't add primitives like int to an NSArray or NSMutableArray class; they only hold objects. The NSNumber class is designed for this situation.
You are leaking memory each time you are allocating an array. Always pair each call to alloc with a matching call to release or autorelease.
The code you want is something like this:
NSMutableArray* array = [[NSMutableArray alloc] init];
for (int i = 0; i < count; i++)
{
NSNumber* number = [NSNumber numberWithInt:i]; // <-- autoreleased, so you don't need to release it yourself
[array addObject:number];
NSLog(#"%i", i);
}
...
[array release]; // Don't forget to release the object after you're done with it
My advice to you is to read the Cocoa Fundamentals Guide to understand some of the basics.
A shorter way you could do is:
NSMutableArray *myArray = [NSMutableArray array];
for(int i = 0; i < 10; i++) {
[myArray addObject:#(i)];
}
NSLog(#"myArray:\n%#", myArray);
hi i want to accept string values into the object of NSArray at run time from the user heres what i tried
-(void)fun
{
NSArray *arr = [[NSArray alloc]init];
for(int i =0;i<3;i++)
{
scanf("%s",&arr[i]);
}
printf("Print values\n");
for(int j =0; j<3;j++)
{
printf("\n%s",arr[j]);
}
}
i am getting an error can you please help me out regarding this and is their any alternative to scanf in objective c.
Thank you
scanf() with a %s format will read the string into a C array, not an NSArray object. You need to read the string into a C array, then make an NSString object to add to your NSArray. You also need to have a mutable array to make your code work. Example:
NSMutableArray *arr = [[NSMutableArray alloc] initWithCapacity:3];
for (int i = 0; i < 3; i++)
{
char buf[100];
scanf("%s", buf);
NSString *str = [NSString stringWithCString:buf encoding:NSASCIIStringEncoding];
[arr addObject:str];
}
You can use NSLog() to print your strings later on.
use NSMutableArray instead;
than you can use also
[arr addObject:tempVar];