Prolong UIPickerView [selectRow: inComponent: animated:]'s animation - ios

Question

I'm using a UIPickerView to display random numbers. The user can press a button, and thus trigger a random selection of a number inside the UIPickerView.
It does not matter how many objects or numbers are being displayed inside the UIPickerView, when I call the method:
[self.picker selectRow:randomRow inComponent:0 animated:YES];
It always gets animated with the same time interval.
Is there any option or method to prolong the animation time interval of above method?
I have tried placing it in an animation block:
[UIView beginAnimations:#"identifier" context:nil];
// code
[UIView commitAnimations];
but this seems to be a dead end.
I have also tried executing it in a completion blocks:
// 0.34f is the approximate defualt apple animation
[UIView animateWithDuration:0.34f animations:^{
[self.picker selectRow:randomRow inComponent:0 animated:YES];
} completion:^(BOOL finished) {
[UIView animateWithDuration:0.34f animations:^{
[self.picker selectRow:randomRow inComponent:0 animated:YES];
} completion:nil];
}];
Any help would be appreciated.

Answer 1

I made a project and play for a while till I find out this tricky solution. It base on the method performSelector:afterDelay
Here is the touch up inside code of your button:
- (void)click:(id)sender
{
int randomRow = <>;//Your random method
int currentRow = [_picker selectedRowInComponent:0];
int i = 0;
while(1)
{
i++;
NSString *rowToSelectString = [NSString stringWithFormat:#"%d", currentRow];
NSDictionary *rowToSelectDictionary = #{#"row":rowToSelectString};
if(randomRow < currentRow)
{
// Go backward
currentRow--;
}
else
{
// Go forward
currentRow++;
}
[self performSelector:#selector(selectRowInPicker:) withObject:rowToSelectDictionary afterDelay:i*0.1];//Change the delay as you want
if(currentRow == randomRow)
{
break;
}
}
}
And the trick:
-(void)selectRowInPicker:(NSDictionary *)rowToSelectDictionary
{
NSInteger row = [[rowToSelectDictionary objectForKey:#"row"] integerValue];
[_picker selectRow:row inComponent:0 animated:YES];
}
This work well for me. Tell me if you're having problem with it.

Answer 2

Finally, I have implemented a "thinner" version of the chosen answer:
- (IBAction)spinTheWheelButtonPressed:(UIButton *)sender
{
for (int i = 0; i < 30; i++) {
NSUInteger randomRow = arc4random_uniform((int)[self.dataSource count]);
[self performSelector:#selector(selectRowInPicker:) withObject:#(randomRow) afterDelay:i*0.1];
}
}
- (void)selectRowInPicker:(NSNumber *)randomRow
{
[self.picker selectRow:[randomRow integerValue] inComponent:0 animated:YES];
}

Answer 3

I had a similar problem , but unfortunately there is no easy way to delay the animation thats as far as I know.
So I went around and placed a UIView on top of the pickerView. I subclassed that view to pass all of its touches to the pickerView and when something was selected I just drew a layer with less opacity in the view where the row would usually come to rest and animated it in a animation block since the selection is always right at the middle of the pickerView.