How to dynamically change the height of a cell in a UITableView? - ios

Question

I have:
A UITableView in my UIViewcontroller
var searchResults: UITableView = UITableView();
A custom UITableViewCell class:
class CellSearchResult: UITableViewCell { ... }
I register my cell for the tableview:
searchResults.registerClass(CellSearchResult.self, forCellReuseIdentifier: "Cell");
I have my tableView method to fill my table:
func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
var cell = tableView.dequeueReusableCellWithIdentifier("Cell", forIndexPath: indexPath) as! CellSearchResult
cell.frame.height = 100; <<<< ERROR
...
}
I would like to change the height of my cell like:
cell.frame.height = 100; <<<< ERROR
How to do this ?

Answer 1

You need to override heightForRowAtIndexPath function. Example:
override func tableView(tableView: UITableView, heightForRowAtIndexPath indexPath: NSIndexPath) -> CGFloat {
return 100
}
EDIT:
If you are not subclassing UITableViewController, you can't access tableView functions unless you conform UITableViewDelegate, UITableViewDataSource protocols. You can do this by
class myViewController: UIViewController, UITableViewDataSource, UITableViewDelegate { ....
.
tableview.delegate = self
tableview.datasource = self

Answer 2

You have to implement the following to increase a particular row height at run time without calling the reloadData()
Example to increase height of row 10:
rowHightUpdateReqd = true
tableView.beginUpdates()
tableView.reloadRowsAtIndexPaths([NSIndexPath(forRow: 10, inSection: 0)], withRowAnimation: UITableViewRowAnimation.Fade)
tableView.endUpdates()
override func tableView(tableView: UITableView, heightForRowAtIndexPath indexPath: NSIndexPath) -> CGFloat {
var rowHight: CGFloat = 50
if rowHightUpdateReqd == true{
rowHight = 100
rowHightUpdateReqd = false
}
return rowHight
}

Answer 3

If the heights of all cells are the same the most efficient way is to set the rowHeight property of the UITableView itself.
tableView.rowHeight = 100.0
There are performance implications to using
tableView:heightForRowAtIndexPath: instead of rowHeight. Every time a
table view is displayed, it calls tableView:heightForRowAtIndexPath:
on the delegate for each of its rows, which can result in a
significant performance problem with table views having a large number
of rows (approximately 1000 or more).
If the cells have variable heights you will need to implement the UITableViewDelegate method tableView:heightForRowAtIndexPath:
func tableView(tableView: UITableView, heightForRowAtIndexPath indexPath: NSIndexPath) -> CGFloat {
var height = // do something to calculate height
return height
}
If you need to do expensive calculations in tableView:heightForRowAtIndexPath: it is also advisable to implement another UITableViewDelegate method, tableView:estimatedHeightForRowAtIndexPath: (available since iOS 7). Any code you put in this method needs to be efficient.
func tableView(tableView: UITableView, estimatedHeightForRowAtIndexPath indexPath: NSIndexPath) -> CGFloat {
return 100.0
}
Providing an estimate the height of rows can improve the user
experience when loading the table view. If the table contains variable
height rows, it might be expensive to calculate all their heights and
so lead to a longer load time. Using estimation allows you to defer
some of the cost of geometry calculation from load time to scrolling
time.

Answer 4

override func tableView(tableView: UITableView!, heightForRowAtIndexPath indexPath: NSIndexPath!) -> CGFloat {
return 100.0;
}