Obj C - populate TableView with objects at specific indexes in array - objective-c

Question

I want to populate my TableView with objects from my array at specific indexes. I thought I could do this by looping an insertObject line and adding the objects that I want to populate the TableView with (at the specific indexes) to a new array and then populating the tableView with the new array but at the end the new array is nil.
The first array is layout like this: email, name, key code, email, name, key code, email, name, key code, etc...... So i want to fill the second array with just the keycodes and then use the key code array and fill the table with it
This is what I have so far:
.h
#property(nonatomic) NSArray *productList;
#property(nonatomic) NSMutableArray *productKeycodes;
.m
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
// Return the number of sections.
// If You have only one(1) section, return 1, otherwise you must handle sections
return 1;
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection: (NSInteger)section
{
// Return the number of rows in the section.
return [self.productList count] / 3;
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *CellIdentifier = #"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];
}
self.productKeycodes = [NSMutableArray new];
bool flag = true;
int index = 3;
int arraySize = [self.productList count];
int numberOfKeycodes = [self.productList count] / 3;
while (flag) {
self.productKeycodes = [self.productList objectAtIndex: index];
//[self.productKeycodes insertObject: self.productList atIndex: index];
if (arraySize > numberOfKeycodes) {
index = index + 3;
arraySize = arraySize - 3;
}else{
flag = false;
}
}
cell.textLabel.text = [NSString stringWithFormat:[self.productKeycodes objectAtIndex: indexPath.row]];
return cell;
}
Breakpoint data after loop is done:
self ProductListViewController * 0x7a2831c0
UIViewController UIViewController
_productListTableView UITableView * 0x7b30c400
_productList __NSArrayM * #"49 elements" 0x78ebe380
_productKeycodes NSMutableArray * nil 0x00000000
numberOfKeycodes int 16
index int 26
arraySize int 13
flag bool true
At get a signal SIGABRT error here:
#import <UIKit/UIKit.h>
#import "AppDelegate.h"
int main(int argc, char * argv[]) {
#autoreleasepool {
//The line below
return UIApplicationMain(argc, argv, nil, NSStringFromClass([AppDelegate class]));//Here!
//The line above
}
}
is my logic wrong and/or is there a better way to do this? Thanks!

Answer 1

replace all code in tableView:cellForRowAtIndexPath: with this:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
static NSString *cellIdentifier = #"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:cellIdentifier];
if (cell == nil) {
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:cellIdentifier];
}
cell.textLabel.text = self.productList[indexPath.row * 3 + 2];
return cell;
}
//

Answer 2

Your logic is wrong.
When you want to add something to the table view you need to do it as follows:
Update you data source i.e. productList in your case.
When you are finished updating the data source, call self.tableView.relaodData()
That is all you need to do to insert data to UITableView

Answer 3

There are better ways to do this
Why do you divide count by 3 and mess with index and flags?
It's ok if you have a good reason but the code to populate your tableview should not belong in cellForRowAtIndexPath.
It is not so clear what you are trying to achieve but the correct way is to update your data source and reload the tableView.

Answer 4

You can create an array of your desired indexes. then in cellForRowAtIndexPath. get the data this way:
int data = datas[indexes[indexPath.row]];
I hope you get the idea