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

animation, ios, uipickerview

Solution

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.

Problem

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.

Original source