iOS：如何将NSArray转换为NSIndexPath

Question

I want to do a batch insertion into UITableview.

MyArray.all() do |datas|
  self.tableView.beginUpdates
  self.tableView.insertRowsAtIndexPaths(datas, withRowAnimation: UITableViewRowAnimationFade)
  self.tableView.endUpdates
  self.myarrayvar += datas
end

'myarrayvar' is an array of MyArray. I tried to refer to apple documentation

and stackoverflow which is similar to my question.

But I really no idea how to convert my datas, to fit into the parameter of insertRowsAtIndexPaths function.

Using rubymotion

Answer 1

Here's one way that I'm currently using:

def insertCellsAtBottom(newData)
  # Get count for the existing data you have.
  currentCount = @data.count

  # Build the indexPaths for the new data, adding to the current count each time.
  # This will make sure you are creating the correct indexes.
  indexPaths = newData.map.with_index do |obj, index|
    NSIndexPath.indexPathForRow(currentCount + index, inSection: 0)
  end

  # Update your datasource and insert the rows.
  self.tableView.beginUpdates
  @data.addObjectsFromArray(newData)
  self.tableView.insertRowsAtIndexPaths(indexPaths, withRowAnimation: UITableViewRowAnimationFade)
  self.tableView.endUpdates
end

Answer 2

Your MyArray contains an array of objects. The method insertRowsAtIndexPaths:withRowAnimation is for telling the tableView that you have added items to your datasource and that it should go and ask for that data at the indexPaths you supply.

The steps you take are:

1. Update your data model
2. Tell the tableView what changes have been made

So for example if you start with an array and add one object your would need to do

# Start with empty data model
my_array = []

# Update the model to have one object
my_array << my_new_object

# Tell the table that you have updated your model by inserting one object at the beginning of the first section
inserted_index_paths = [ NSIndexPath.indexPathForRow(0, inSection: 0]) ]
self.tableView.insertRowsAtIndexPaths(inserted_index_paths, withRowAnimation: UITableViewRowAnimationFade)

If you then inserted an object at the end again it would look very similar except that the newly inserted index path would be NSIndexPath.indexPathForRow(1, inSection: 0) as you would now be telling the tableView that you inserted a second object into the first section

---

Old Answer

You should do something like

index_paths = MyArray.map { |index| NSIndexPath.indexPathForRow(index, inSection: 0) }

self.tableView.beginUpdates
self.tableView.insertRowsAtIndexPaths(index_paths, withRowAnimation: UITableViewRowAnimationFade)
self.tableView.endUpdates

Answer 3

in obj-c this is the way to do it... if you get your datas from an NSMutableArray, just make your operation in it.

for example, i got

array = @[@"text1", @"text2", @"text4"];

for my cell, i'm calling in cellForRowAtIndexPath method:

[cell setText:array[indexPath.row]];

in my array i'm making :

array[2] = @"text3";

and then :

[self.tableView reloadData];

I didn't test this but it's the good way to insert a new row.