Hey guys & girls,
Im wondering how I can find the object count of a specific type of object in an array.
For example, i have 6 'clouds' in NSMutableArray at random locations, I also have 4 'dragons' in this NSMutableArray.
How can i gather the integer 6?
I was thinking something along the lines of:
int z = [[SomeClass *clouds in _somearray] count];
Any assistance would be greatly appreciated.
Thnx,
Oliver.
Yet another way is in using blocks:
Class cloadClass = NSClassFromString(#"Cloud");
NSArray *a = /* you array with clouds and dragons */;
NSIndexSet *clouds = [a indexesOfObjectsPassingTest:
^(id obj, NSUInteger idx, BOOL *stop) {
return [obj isKindOfClass:cloadClass];
}];
// now we can count clouds
NSLog(#"%d", [clouds count]);
// but also we now can return our clouds immediately and
NSLog(#"%#", [a objectsAtIndexes:clouds]);
int result = 0;
for (NSObject *object in _somearray) {
if ([object isKindOfClass:[SomeClass class]])
result++;
}
result is the count you are looking for
If you're looking for how many times a specific instance of an object appears, you can do:
NSCountedSet *counts = [NSCountedSet setWithArray:myArrayOfObjects];
NSUInteger count = [counts countForObject:myObject];
Otherwise you'd just have to loop through the array manually and count.
Related
I have two arrays:
array1=[1,2,3,4,5,6,7,8,9,10,11]
array2=[1,2]
I want to compare weather elements in "array2" is present in "array1" or not.
If yes then I need to run a function, otherwise exit.
How to do it?
I have get the common items like this:-
NSMutableSet *idSet=[NSMutableSet setWithArray:Array1];
[idSet intersectSet:[NSSet setWithArray:Array2]];
NSArray *Common_array=[idSet allObjects];
in common array you can get the same object that are present in both array and is 0 object in
Common_array than in both array there is none on object that are same.
What about enumerating over array1?
Something along the lines of
NSArray *array1 = ...;
NSArray *array2 = ...;
[array1 enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) {
if ([array2 containsObject: obj]) {
// Run the function you wanted to
}
}];
An easy logic way to do this would be a for loop:
for(int a = 0; a < array1.count; a++) {
for(int b = 0; b < array2.count; b++) {
if([[array1 objectAtIndex:a] isEqualToString:[array2 objectAtIndex:b]]) {
//do something here
}
}
}
I want to get the index of an object within the NSMutableArray of categories.
The category object has an attribute "category_title" and I want to be able to get the index by passing the value of category_title.
I have looked through the docs and can't find a simple way to go about this.
NSArray does not guarantee that you can only store one copy of a given object, so you have to make sure that you handle that yourself (or use NSOrderedSet).
That said, there are a couple approaches here. If your category objects implement isEqual: to match category_title, then you can just use -indexOfObject:.
If you can't do that (because the category objects use a different definition of equality), use -indexOfObjectPassingTest:. It takes a block in which you can do whatever test you want to define your "test" - in this case, testing category_title string equality.
Note that these are all declared for NSArray, so you won't see them if you are only looking at the NSMutableArray header/documentation.
EDIT: Code sample. This assumes objects of class CASCategory with an NSString property categoryTitle (I can't bring myself to put underscores in an ivar name :-):
CASCategory *cat1 = [[CASCategory alloc] init];
[cat1 setCategoryTitle:#"foo"];
CASCategory *cat2 = [[CASCategory alloc] init];
[cat2 setCategoryTitle:#"bar"];
CASCategory *cat3 = [[CASCategory alloc] init];
[cat3 setCategoryTitle:#"baz"];
NSMutableArray *array = [NSMutableArray arrayWithObjects:cat1, cat2, cat3, nil];
[cat1 release];
[cat2 release];
[cat3 release];
NSUInteger barIndex = [array indexOfObjectPassingTest:^BOOL(id obj, NSUInteger idx, BOOL *stop) {
if ([[(CASCategory *)obj categoryTitle] isEqualToString:#"bar"]) {
*stop = YES;
return YES;
}
return NO;
}];
if (barIndex != NSNotFound) {
NSLog(#"The title of category at index %lu is %#", barIndex, [[array objectAtIndex:barIndex] categoryTitle]);
}
else {
NSLog(#"Not found");
}
Not sure that I understand the question but something like this might work (assuming the Mutable Array contains objects of Class "Category"):
int indx;
bool chk;
for (Category *aCategory in theArray)
{
chk = ([[aCategory category_title] isEqualToString:#"valOfCategoryTitle"])
if ( chk )
indx = [theArray indexOfObject:aCategory];
}
Try this code much more simpler:-
int f = [yourArray indexOfObject:#"yourString"];
I want to take the values from NSMutableArray but want to read from last index to 1st index
thank you
for (id someObject in [someArray reverseObjectEnumerator])
{
//do your thing
}
2 other options:
Simple for-loop (surely not recommended):
for (int i = [array count]-1; i >= 0; ++i)
id value = [array objectAtIndex: i];
Block-based enumeration:
[array enumerateObjectsWithOptions: NSEnumerationReverse
usingBlock: ^(id obj, NSUInteger idx, BOOL *stop){
//do something
}];
Mark's answer is useful, but this form may be useful when you want to mutate the array:
while ([arr count]) {
id obj = [arr lastObject];
// use obj
[arr removeLastObject];
}
I am stuck in a stupid mess...
I want to get not only the value of an array but also the index of the values.
In PHP it's simple: foreach($array as $key->$value) Here $key will contain the index value.
Isn't there a similar approach in objective c?
How else could I achieve this?
Please help! :((
Arrays not like in php are numbered 0-size of array. I guess you talking about dictionary's. If so you can get array of key with [dict allKeys].
so something like this should work:
for(id key in [dict allKeys]){
id value = [dict objectForKey:key];
}
If you're on iOS4 you can do
[array enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop)
{
NSLog(#"%# is at index %u", obj, idx);
}];
on iOS 3.x you can do
NSUInteger idx = 0;
for (id obj in array)
{
NSLog(#"%# is at index %u", obj, idx);
idx++
}
for (i=0;i<array.count;i++)
{
NSLog(#"Index=%d , Value=%#",i,[array objectAtIndex:i]);
}
Use this its simpler...
hAPPY cODING...
I'm unable to test it, but I think I did do something similar the other night. From this wiki it looks like you can do something like
for(id key in d) {
NSObject *obj = [d objectForKey:key]; // We use the (unique) key to access the (possibly non-unique) object.
NSLog(#"%#", obj);
}
int arraySize = array.count;
// No need to calculate count/size always
for (int i=0; i<arraySize; i++)
{
NSLog(#"Index=%d , Value=%#",i,[array objectAtIndex:i]);
}
I have a NSMutableArray:
NSMutableArray *temp = //get list from somewhere.
Now there is one method objectAtIndex which returns the object at specified index.
What I want to do is that, I want to first check whether an object at specified index exists or not. If it exists than I want to fetch that object. Something like:
if ([temp objectAtIndex:2] != nil)
{
//fetch the object
}
But I get exception at the if statement saying that index beyond bound.
Please anyone tell me how to achieve this.
you cannot have 'empty' slots in an NSArray. If [myArray count]==2 ie array has two elements then you know for sure that there is an object at index 0 and an object at index 1. This is always the case.
Check the length first using the count method.
if ([temp count] > indexIWantToFetch)
id object = [temp objectAtIndex:indexIWantToFetch];
you could do this way:
When you initialize, do something like:
NSMutableArray *YourObjectArray = [[NSMutableArray alloc] init];
for(int index = 0; index < desiredLength; index++)
{
[YourObjectArray addObject:[NSNull null]];
}
Then when you want to add but check if it already exists, do something like this:
YourObject *object = [YourObjectArray objectAtIndex:index];
if ((NSNull *) object == [NSNull null])
{
/// TODO get your object here..
[YourObjectArray replaceObjectAtIndex:index withObject:object];
}
Just check that the index is >= 0 and < count
Returns the number of objects currently in the receiver.
- (NSUInteger)count
int arrayEntryCount = [temp count];
First of all you check the length of array-
NSMutableArray *temp = //get list from somewhere.
now check-
if(temp length)
{
Your objectclass *obj = [temp objectAtIndex:indexnumber];
// indexnumber is 0,1,2 ,3 or anyone...
}