Iterating through an NSArray and storing items in groups of 12 - ios

I've definitely tried to do my due diligence on this one but keep coming up short. I have an array of objects that I have parsed and I want to iterate through these and store them. Assuming the array is 144 objects (just an example), I want to store it in groups of 12 to display in a tableview cell. Actually of those 12 objects in the array I'll likely only be displaying 3-4 in the cell, but all of those objects in the detail view.
To help explain what I mean (sorry if it hasn't made sense at this point) here's some of the code I've got that is getting the data.
NSMutableArray *objectsArray = [[NSMutableArray alloc] initWithCapacity:0];
for (TFHppleElement *element in objectsNode) {
PHSingleEvent *singleEvent = [[PHSingleEvent alloc]init];
[objectsArray addObject:singleEvent];
singleEvent.title = [[element firstChild] content];
}
This pulls down the entire array of objects (an unknown number but definitely a multiple of 12). How would I go about storing 12 objects at a time into a single event?
I can log the info with
PHSingleEvent *firstObject = [objectsArray objectAtIndex:0] // this one is null
PHSingleEvent *eventStartTime = [objectsArray objectAtIndex:1];
PHSingleEvent *eventEndTime = [objectsArray objectAtIndex:2];
...
PHSingleEvent *lastObject = [objectsArray objectAtIndex:11];
NSLog(#"single object of event: %#", eventStartTime.startTime);
NSLog(#"single object of event: %#", eventEndTime.endTime);
etc...
But the array keeps going past 12. I want to iterate up through each 12 objects and store those values, preferably as strings to be displayed in a cell and detail view.
Any ideas?
Thanks much in advance and I will be here to answer any questions if I was unclear.
C.

How about using a for loop? Assuming that each event object has 12 sub-objects (i.e. indices 0 - 11) you could achieve storing it by using a mod function. For example:
NSMutableArray *eventArray = [[NSMutableArray alloc] init];
for(int i=0; i<objectArray.count/12;i++){
int offset = 12*i;
NSMutableArray *event = [objectsArray subarrayWithRange:NSMakeRange(offset, 12)];
[eventArray addObject:event];
}
So now eventArray has n arrays, each of 12 objects (where n = totalObjects/12)
EDIT: A better idea would be to use NSDictionary. For example:
NSMutableArray *eventArray = [[NSMutableArray alloc] init];
for(int i=0; i<objectArray.count/12;i++){
int offset = 12*i;
NSDictionary *tempDict = [[NSDictionary alloc] initWithObjectsAndKeys: [objectsArray objectAtIndex: offset], #"eventStartTime", [objectsArray objectAtIndex: offset+1], #"eventEndTime", ..., [objectsArray objectAtIndex: offset+11, #"lastObject",nil];
[eventArray addObject:tempDict];
}
Then you can access each of the above objects using a similar statement as shown below:
PHSingleEvent *eventStartTime = [[eventArray objectAtIndex: index] objectForKey: #"eventStartTime"];
Hope this helps

This method will return an array of smaller arrays based on the group size you specify.
- (NSMutableArray*)makeGroupsOf:(int)groupSize fromArray:(NSArray*)array
{
if (!array || array.count == 0 || groupSize == 0)
{
return nil;
}
NSMutableArray *bigGroup = [[NSMutableArray alloc] init];
for (int i = 0; i < array.count; )
{
NSMutableArray *smallGroup = [[NSMutableArray alloc] initWithCapacity:groupSize];
for (int j = 0; j < groupSize && i < array.count; j++)
{
[smallGroup addObject:[array objectAtIndex:i]];
i++;
}
[bigGroup addObject:smallGroup];
}
return bigGroup;
}
I haven't tested it or anything though. After you have the big array with the smaller array(s) it is just a matter of filling each cell with any desired number of objects from the sub arrays.
Note: You might want to handle the cases when the array is empty, null or the group size is 0 differently.

Related

Load UITableView sections by NSDate from NSDictionary?

I have an NSArray of NSDictionaries in my app. In each dictionary I hold an NSDate called "RunDate." The problem I am having now is that the code I am trying to do it with is very inefficient. Basically I only want one section per date out of all the dictionaries. Then in each section (sorted by that date), I would load the appropriate dictionary that had that date.
In the code below I made a new NSArray of NSDictionarys which held a date and number of that date (so I could know how many rows are in each section). The problem is, this code looks and feels very inefficient and I was wondering if there were any ways my code is incorrect or could be improved upon. There can be over 500 entries and the code I have now would be very slow. Does anyone have any suggestions on it?
runArray = [[NSMutableArray alloc] init];
runArray = [[[NSUserDefaults standardUserDefaults] arrayForKey:#"RunArray"] mutableCopy];
runDictTableArray = [[NSMutableArray alloc] init];
for (NSDictionary *dict in runArray) {
NSDictionary *runInfoDict = [[NSMutableDictionary alloc] init];
NSDate *theDate = [dict objectForKey:#"RunDate"];
//Check if we already have this date in the saved run array
BOOL goToNextDict = FALSE;
for (NSDictionary *savedDict in runDictTableArray) {
if ([theDate compare:[savedDict objectForKey:#"RunDate"]] == NSOrderedSame) {
goToNextDict = TRUE;
break;
}
}
if (goToNextDict)
continue;
////////////////////////////
//Now we check how many more we have of this date
int numbOfDate = 1;
int index = (int)[runArray indexOfObject:dict];
for (int i = index; i < [runArray count]; i++) {
NSDictionary *dictInner = [runArray objectAtIndex:i];
if ([theDate compare:[dictInner objectForKey:#"RunDate"]] == NSOrderedSame) {
numbOfDate++;
}
}
////////////////////////////
[runInfoDict setValue:[NSNumber numberWithInt:numbOfDate] forKey:#"DateAmount"];
[runInfoDict setValue:theDate forKey:#"Date"];
[runDictTableArray addObject:runInfoDict];
}
Some suggestions:
You probably only need 1 NSMutableDictionary, rather than a NSMutableArray of NSDictionary. While looping through runArray, check if your dictionary has a value for your date (objectForKey returns a value). If it does, add 1 to the count. If it does not, add that date as a key to the dictionary with a value of 1. This way, you won't have to do the inner loop to get the number of times a date occurs. You won't need the 'go to next dictionary' logic either, I would think.
runArray = [[NSMutableArray alloc] init]; doesn't really do anything since you're immediately re-assigning runArray.
Consider using NSInteger over regular int, NSInteger will give you the appropriate size for whatever architecture your app is running on.
There's some cool syntax shortcuts you might like. You can avoid [runInfoDict setValue:[NSNumber numberWithInt:numbOfDate]... by simply writing [runInfoDict setValue:#(numbOfDate) ..., which will put the value into NSNumber for you.

Compare the unique index value with another array in objective C

There is an array having same objects in single array , i need to compare these array’s index with another array.. Give me a help.
Something like:
NSMutableArray *latArray =
[NSMutableArray arrayWithObjects:#“43.20,#“43.23”,#“43.24”,#“43.20”,nil];
NSMutableArray *lngArray =
[NSMutableArray arrayWithObjects:#“76.90”,#“76.94”,#“76.92”,#“76.90”,nil];
NSMutableArray *imagesArray =
[[NSMutableArray alloc] initWithObjects:#"1.jpg", #"2.jpg”,#“3.jpg”,#“4.jpg”,nil];
resultResult = #"1.jpg", #“4.jpg” // because the index 0 and index 3 same values in both array.
I would wrap your coordinates into location objects and use them as the keys in a dictionary. This would allow to check for duplicate coordinates, like this:
NSMutableDictionary *results = [[NSMutableDictionary alloc] init];
for (int i = 0; i < [imagesArray count]; i++)
{
// Wrap coordinates into a NSValue object
// (CLLocationCoordinate2D is a C-struct that cannot be used as a dictionary key)
// (CLLocation also does not implement required methods to be usable as a dictionary key)
NSValue *loc = [NSValue valueWithMKCoordinate:CLLocationCoordinate2DMake(
((NSNumber)[latArray objectAtIndex:i]).doubleValue,
((double)[lngArray objectAtIndex:i]).doubleValue)];
// 1. If you only want the first occurrence of a specific location, use this:
if ([results objectForKey:loc] == nil)
{
[results setObject:[imagesArray objectAtIndex:i] forKey:loc];
}
// 2. Or, if you want the last occurrence of a specific location, use this:
[results setObject:[imagesArray objectAtIndex:i] forKey:loc];
}
I think you are trying the check for the same objects in an array. If so do the following.
for(int i=0;i<yourarray.count;i++)
{
NSString *yourstring=[yourarray objectatindex:i];
for(int k=0;k<yourarray.count;k++)
{
if(i!=k)
{
NSString *yourstring2=[yourarray objectatindex:k];
if([yourstring isEqualtostring yourstring2])
{
//now you got equal objects. do what ever you want here
}
}
}
}

Sort NSArray in descending order

I have an NSArray with 4 objects, let's say 1, 2, 3 and 4. I want to sort this array in ascending order, but with a randomly selected starting number. For instance; 2, 3, 4 and 1 or 4, 1, 2 and 3.
How can I do this?
What I have thus far:
NSArray *playersArray = [_players allKeys];
NSSortDescriptor *sortPlayerArray = [[NSSortDescriptor alloc] initWithKey:nil ascending:YES];
playersArray = [playersArray sortedArrayUsingDescriptors:#[sortPlayerArray]];
This results in 1, 2, 3, 4, obviously. I am also able to randomly order the players, like so:
activePlayersArray = [_players allKeys];
NSMutableArray *temp = [[NSMutableArray alloc] initWithArray:activePlayersArray];
int count = (int)[temp count];
for (int i = 0; i < count; ++i) {
int nElements = count - i;
int n = (arc4random() % nElements) + i;
[temp exchangeObjectAtIndex:i withObjectAtIndex:n];
}
activePlayersArray = [NSArray arrayWithArray:temp];
So how can I "combine" these two to get the results I want?
Hope you guys can help me.
Thanks!
This is really an algorithm problem, not an iOS problem. Here are the steps to follow
make a note of your randomly selected number
Sort the array in descending order as you normally would (as in Sort an NSArray in Descending Order)
Then split the array at the location of your special number (similar to How to split an NSArray into two equal pieces?)
after the split create a new array where the second piece now comes first
Another solution is to create a circular array of sorted elements and then traverse the array in reverse order.
I think this is what #Konsol intends, with a couple fixes: (1) it looks like the OP wants the order to be ascending, and (2) the array split in the other answer is at the midpoint. But I think the spirit is correct...
// Start with an unsorted (immutable?) input array of numbers (or any object
// that implements compare:.
// Pick a random location and produce an output array as described by the OP
NSMutableArray *mutableArray = [inputArray mutableCopy]; // if its not mutable already
[mutableArray sortUsingSelector:#selector(compare:)];
NSInteger inputIndex=arc4random_uniform(mutableArray.count);
NSArray *start = [mutableArray subarrayWithRange:NSMakeRange(inputIndex, mutableArray.count-inputIndex)];
NSArray *end = [mutableArray subarrayWithRange:NSMakeRange(0, inputIndex)];
NSArray *outputArray = [start arrayByAddingObjectsFromArray:end];
NSLog(#"%#", outputArray);
int count = (int)[activePlayersArray count];
int n = (arc4random() % nElements) + i;
NSMutableArray *temp = [[NSMutableArray alloc] init];
for (int i = 0; i < count; ++i) {
int nElements = count - i;
[temp addObject:[activePlayersArray objectAtIndex:(n-i)%count]];
}
activePlayersArray = [NSArray arrayWithArray:temp];
Hope it works!

Adding objects to dictionary in a loop overwrites previous values

I have three NSArrays, and I want to combine them all into a single NSDictionary. The problem is that as I iterate through the arrays and create the dictionary, it overwrites the previous object. In the end I only have one object in my dictionary. What am I doing wrong? Here's my code:
NSMutableDictionary *dict = [[NSMutableDictionary alloc] init];
for(int i=0; i<[array0 count]; i++) {
[dict setObject:[array0 objectAtIndex:i]
forKey:#"one"];
[dict setObject:[array1 objectAtIndex:i] f
orKey:#"two"];
[dict setObject:[array2 objectAtIndex:i]
forKey:#"three"];
}
Maybe this will clarify what I mean...
this is the result I'm going for:
{one = array0_obj0, two = array1_obj0, three = array2_obj0},
{one = array0_obj1, two = array1_obj1, three = array2_obj1},
{one = array0_obj2, two = array1_obj2, three = array2_obj2},
etc
Thanks
Issue
You are inserting and replacing the same object at the specific key. So all what dictionary has is its last object at the last index.
Solution
Use this code to add the three arrays into one dictionary with your specific keys.
NSDictionary *yourDictinary = #{#"one": array0, #"two": array1, #"three": array3};
Edit
If you need to add objects of your NSMutableArrays to one NSDictionary you can follow the answer posted by #ElJay, but that's not a good practice, since you are dealing with multiple objects with unique keys.
Update
To do that thing, we are talking about a single NSMutableArray and multiple NSDictinarys.
Follow this code:
NSMutableArray *allObjects = [NSMutableArray new];
for(int i=0; i<[array0 count]; i++) {
dict = #{#"one": array0[i], #"two": array1[i], #"three": array2[i]};
[allObjects addObject:dict];
}
Here ya go:
NSMutableDictionary *dict = [[NSMutableDictionary alloc] init];
for(int i=0; i<[array0 count]; i++) {
[dict setObject:[array0 objectAtIndex:i] forKey:[NSString stringWithFormat:#"arr0_%d", i]];
[dict setObject:[array1 objectAtIndex:i] forKey:[NSString stringWithFormat:#"arr1_%d", i]];
[dict setObject:[array2 objectAtIndex:i] forKey:[NSString stringWithFormat:#"arr2_%d", i]];
}
Edit - with revised question:
self.array0 = #[#"Array0_0",#"Array0_1",#"Array0_2", #"Array0_3"];
self.array1 = #[#"Array1_0",#"Array1_1",#"Array1_2", #"Array1_3"];
self.array2 = #[#"Array2_0",#"Array2_1",#"Array2_2", #"Array2_3"];
NSMutableArray *finalArray = [[NSMutableArray alloc] init];
for (int i=0; i< [_array0 count]; i++) {
NSDictionary *dict = #{#"one":[_array0 objectAtIndex:i], #"two":[_array1 objectAtIndex:i],#"three":[_array2 objectAtIndex:i]};
[finalArray addObject:dict];
}
NSLog(#"finalArray = %#", [finalArray description]);
You're reusing the keys ("one", "two" and "three") through each iteration of the loop. Keys in an NSDictionary have to be unique.
If you want many dictionary but only three keys, you should save each dict in an array.

Use a for loop to set values in an array

I have a UITableViewController that uses an array with values for every entry in the rows.
I want to set the values of that array by iterating over values read from a JSON file.
This is the new method I have created to read that data into an array and return it to my view controller. I don't know where to return the array, or how to really set it.
+(NSArray *)setDataToJson{
NSDictionary *infomation = [NSDictionary dictionaryWithContentsOfJSONString:#"Test.json"];
NSArray *test = [infomation valueForKey:#"Animals"];
for (int i = 0; i < test.count; i++) {
NSDictionary *info = [test objectAtIndex:i];
NSArray *array = [[NSArray alloc]initWithObjects:[Animal animalObj:[info valueForKey:#"AnimalName"]
location:[info valueForKey:#"ScientificName"] description:[info valueForKey:#"FirstDesc"] image:[UIImage imageNamed:#"cat.png"]], nil];
return array;
I know that my animalObj function worked when the data was local strings(#"Cat") and my dictionaryWithContentsOfJSONString works because I have tested, but I haven't used this function to set data to an array, only to UILabels, so this is where I am confused, on how to set this data into an array. But still use the For loop.
You want to use an instance of
NSMutableArray,
which will let you incrementally add elements to the array as you
iterate with the for-loop:
...
NSMutableArray *array = [NSMutableArray array];
for (int i = 0; i < test.count; i++) {
NSDictionary *info = [test objectAtIndex:i];
Animal *animal = [Animal animalObj:[info valueForKey:#"AnimalName"]
location:[info valueForKey:#"ScientificName"]
description:[info valueForKey:#"FirstDesc"]
image:[UIImage imageNamed:#"cat.png"]];
[array addObject:animal];
}
return array;
Because NSMutableArray is a subclass of NSArray, there's no need change the return type of your method.

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