Question

I have code that scans and returns NSString like this:

NSString *GetText = [[NSString alloc] init];
NSString *ScannedText;
NSScanner *TheScanner = [NSScanner scannerWithString:somLongString];
int start=0;
int index=0;
int ObjectCount;
char c;
for (int i = 0; i < [somLongString length] ; i++) {
    c = [somLongString characterAtIndex:i];
    if (c == '=') {
        start = i+1;
        [TheScanner setScanLocation:start];
        [TheScanner scanUpToString:@"&" intoString:&GetText];
        NSLog( @"%@",GetText);
        [UserValuesObject insertObject:GetText  atIndex:index];
        NSLog(@"%@",[UserValuesObject objectAtIndex:index]);
        index++;
    }
}

Now I want to add the GetText object I am creating each time to an array. When I try printing the first:

NSLog(@"%@",GetText); 

it works! But when I am tring to add it to the object and then print (for debug) I am getting null on each print of the log:

NSLog(@"%@",[UserValuesObject objectAtIndex:index]);

any ideas?

Answer 1

You may not have initialized your array properly (or at all), try this (syntax improvements included):

NSString *getText = [NSString string];
NSScanner *scanner = [NSScanner scannerWithString:someLongString];
NSUInteger start = 0;
NSUInteger index = 0;
NSMutableArray *userValuesObject = [NSMutableArray array];
//  You should save the length of someLongString before starting the loop 
//   so that each iteration doesn't have to call length to see if i has 
//   reached length yet
for (int i = 0, len = [someLongString length]; i < len; ++i) {
    if ([somLongString characterAtIndex:i] == '=') {
        [scanner setScanLocation:(i + 1)];
        [scanner scanUpToString:@"&" intoString:getText];
        NSLog(@"%@", GetText);
        [userValuesObject insertObject:getText atIndex:index];
        NSLog(@"%@", [userValuesObject objectAtIndex:index]);
        ++index;
    }
}

From NSMutableArray Docs:

insertObject:atIndex:

Parameters

anObject – The object to add to the array’s content. This value must
not be nil.

Important: RaisesanNSInvalidArgumentException if anObject is nil.

index – The index in the array at which to insert anObject. This
value must not be greater than the count of elements in the array.

Important: Raises an NSRangeException if index is greater than the number of elements in the array.

If index is already occupied, the objects at index and beyond are
shifted by adding 1 to their indices to make room. Note that NSArray
objects are not like C arrays. That is, even though you specify a size
when you create an array, the specified size is regarded as a “hint”;
the actual size of the array is still 0. This means that you cannot
insert an object at an index greater than the current count of an
array. For example, if an array contains two objects, its size is 2,
so you can add objects at indices 0, 1, or 2. Index 3 is illegal and
out of bounds; if you try to add an object at index 3 (when the size
of the array is 2), NSMutableArray raises an exception.