How to properly override reloadRowsAtIndexPaths:withRowAnimation? - ios

Question

I would like to create a special animation for when I'm reloading the rows of a UITableView. The thing is I don't want to use this animation all the time, as I am sometimes using built-in animation for reloading the rows.
So how can I do this? By overriding reloadRowsAtIndexPaths:withRowAnimation in my own UITableView implementation? How?
Or maybe there is a better way to get my own animation while reloading a row?

Answer 1

I think you should not override reloadRowsAtIndexPaths:withRowAnimation. Just implement a custom method reloadRowsWithMyAnimationAtIndexPaths:in UITableView's category and use it when it is needed.
But if you want to override this method in UITableView's subclass, you could do this:
- (void)reloadRowsAtIndexPaths:(NSArray *)indexPaths
withRowAnimation:(UITableViewRowAnimation)animation {
if (self.useMyAnimation)
[self reloadRowsWithMyAnimationAtIndexPaths:indexPaths];
else
[super reloadRowsAtIndexPaths:indexPaths withRowAnimation:animation];
}
self.useMyAnimation is just a flag (BOOL property) that indicates what animation to use. Set this flag before reload operation.
For 2 or more customAnimations you could implement enum:
enum MyTableViewReloadAnimationType {
case None
case First
case Second
case Third
}
Then make a MyTableViewReloadAnimationType property (for example, reloadAnimationType) and select an appropriate animation method with switch:
var reloadAnimationType = MyTableViewReloadAnimationType.None
override func reloadRowsAtIndexPaths(indexPaths: [AnyObject], withRowAnimation animation: UITableViewRowAnimation) {
switch self.reloadAnimationType {
case .None:
super .reloadRowsAtIndexPaths(indexPaths, withRowAnimation:animation)
default:
self .reloadRowsAtIndexPaths(indexPaths, withCustomAnimationType:self.reloadAnimationType)
}
}
func reloadRowsAtIndexPaths(indexPaths: [AnyObject], withCustomAnimationType animationType: MyTableViewReloadAnimationType) {
switch animationType {
case .First:
self .reloadRowsWithFirstAnimationAtIndexPaths(indexPaths)
case .Second:
self .reloadRowsWithSecondAnimationAtIndexPaths(indexPaths)
case .Third:
self .reloadRowsWithThirdAnimationAtIndexPaths(indexPaths)
}
}
You could call the custom method reloadRowsAtIndexPaths:withCustomAnimationType: directly:
self.tableView .reloadRowsAtIndexPaths([indexPath], withCustomAnimationType: MyTableViewReloadAnimationType.First)
Inside the custom method you need to get a current cell and a new cell with method of dataSource:
func reloadRowsWithFirstAnimationAtIndexPaths(indexPaths: [AnyObject]) {
for indexPath in indexPaths {
var currentCell = self .cellForRowAtIndexPath(indexPath as! NSIndexPath)
var newCell = self.dataSource .tableView(self, cellForRowAtIndexPath: indexPath as! NSIndexPath)
var newCellHeight = self.delegate .tableView(self, heightForRowAtIndexPath: indexPath)
var frame: CGRect = currentCell.frame
frame.size.height = newCellHeight
newCell.frame = frame
self .replaceCellWithFirstAnimation(currentCell!, withAnotherCell: newCell);
}
}
func replaceCellWithFirstAnimation(firstCell : UITableViewCell, withAnotherCell secondCell: UITableViewCell) {
var cellsSuperview = firstCell.superview!
//make this with animation
firstCell .removeFromSuperview()
cellsSuperview .addSubview(secondCell)
}
You need to handle a situation when newCell's height > or < then currentCell's height. All other cells frames must be recalculated. I think it could be done with beginUpdates and endUpdates methods. Call them before the manipulation with cells.