Question

Time profiler shows the most time consuming operation in my app is loading UITableViewCells from nib files. The most expensive of which involves loading a UITableViewCell with a 4KB image.

I am loading the UITableViewCell from the nib with the following code:

    [[NSBundle mainBundle] loadNibNamed:@"UITableViewCellPortrait" owner:self options:NULL];
    cell = portraitCell;
    self.portraitCell = nil;

Has anyone compared the difference between creating a view programmatically or loading a UITableViewCell from a nib?

EDIT:
I compared the time profile of repeated runs of loading the UITableViewCell from a nib and creating the view programmatically. My test involved alternating between two UITableViews about 10 times in the span of 3-5 seconds. In each test, loading the UITableViewCell programmatically was substantially faster, between 2x to 6x faster.

Can anyone corroborate these results?

EDIT:
I updated the nib loading code to only load the nib file once and use a cached version for subsequent calls.

    if (self.UITableViewPortaitNib == nil) {
        self.UITableViewPortaitNib = [UINib nibWithNibName:@"UITableViewCellPortrait" bundle:[NSBundle mainBundle]];
    }

    self.UITableViewPortaitNib instantiateWithOwner:self options:NULL];
    cell = portraitCell;
    self.portraitCell = nil;

I also used the automation instrument to create more consistent runs and the results still suggest loading UITableViewCells programmatically is faster than loading UITableViewCells for a nib. The average running time for loading UITableViewCells from a nib was around 90ms, while the average running time for creating the UITableViewCell programmatically was 50ms.

Answer 1

Try creating a UINib object once and then sending it instantiateWithOwner:options: each time you need to create a new cell. From the UINib Class Reference:

For example, if your table view uses a nib file to instantiate table view cells, caching the nib in a UINib object can provide a significant performance improvement.