UITableView Section is Repeating Data - ios

Question

This has been killing me for a few hours now. I have a UITableViewController that has multiple data sections. My data source is simply an Array.
The problem I'm running into is that each section is repeating data from the array starting from the first index instead of "slicing" it as I expect it should.
Simplified example:
let sections = ["Section A", "Section B"]
let counts = [3, 5]
let source = ["a","b",c","d","e","f","g","h"]
// Output in simulator:
# Section A
- a
- b
- c
# Section B
- a
- b
- c
- d
- e
- and so on...
I would expect that "Section B" would be the next 5 results starting at "d" and not restart from the first index.
The relevant code is pretty standard stuff:
override func numberOfSectionsInTableView(tableView: UITableView) -> Int {
return sections.count // returns 2
}
override func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return counts[section] // returns correct data
}
override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
let data = source[indexPath.row]
let cell = tableView.dequeueReusableCellWithIdentifier("Cell", forIndexPath: indexPath) as! MyTableViewCell
// some cell formatting, populate UILabels, etc
cell.testLabel.text = data["test"].string
return cell
}
override func tableView(tableView: UITableView, viewForHeaderInSection section: Int) -> UIView? {
let headerCell = tableView.dequeueReusableCellWithIdentifier("Header") as! MyTableViewHeaderCell
headerCell.backgroundColor = UIColor.grayColor()
headerCell.testHeaderLabel.text = sections[section]
return headerCell
}
Initial searching of SO led me to believe it's a cell reuse issue but after overriding prepareForReuse in my cell class, I don't think thats it.
Expected Results
# Section A
- a
- b
- c
# Section B
- d
- e
- f
- g
- h
Like I said, I'm expecting that dividing the TableView data in to sections would keep a reference to the array pointer and continue where it left off instead of starting back at 0 for each section.
Any thoughts or suggestions?

Answer 1

indexPath.row always returns the row-number inside a section.
In your second section, you need to add the number of rows displayed in all sections before.
Change let data = source[indexPath.row] to something like this:
let data = source[indexPath.row+counts[0]]
If you add more sections, this will be a bit more complicated to calculate.
Other idea:
If it is possible, you could rearrange your array. You could make a two-dimensional array. The main array would include arrays with the data for each section.
To display it, you' need to use indexPath.section, too.
dataArray[indexPath.section][indexPath.row]

Answer 2

Using the idea of FelixSFD, but with a little logical modification, so you can work dynamically:
Change this:
let data = source[indexPath.row]
for this:
var countIndex = indexPath.row
for section in 0...indexPath.section {
countIndex += counts[section]
}
let data = source[countIndex]
Be careful with this approach because you may have some performance issues on large tableViews.

Answer 3

If you can rearrange your array:
change
let source = ["a","b",c","d","e","f","g","h"]
into
let source = [["a","b","c"],["d","e","f","g","h"]]
and change
let data = source[indexPath.row]
into
let data = source[indexPath.section][indexPath.row]

Answer 4

I had the same problem, but with more complex situation, and i needed more dynamically way of doing it. Sure i could rearrange my data, to use two-dimensional array, but i don't want to handle it later. So i did it like this.
I am pulling my data from firebase, so i never know, how many sections/arrays i will have.
Creating an array, to insert amount of items in array.
var counterTableView = [Int]()
Filling array with 0, without doing it, i was getting errors later. (Index out of range)
override func numberOfSections(in tableView: UITableView) -> Int {
for i in 0...Array(Set(self.sections)).count {
counterTableView.insert(0, at: i)
}
counterTableView.removeLast(counterTableView.count-Array(Set(self.sections)).count-1)
return Array(Set(self.sections)).count
}
Next step, is to fill the amount of items in one section in array
override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
counterTableView[section+1] = counts[section] + counterTableView[section]}
Last step, showing the data in cell
override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
cell.textLabel.text = source[indexPath.row+counterTableView[indexPath.section]]}