UIPicker single component to display multiple arrays - ios

Question

first comment so I hope Im doing this right.
I'm having a fight with a UIPicker. I am trying to display 2 columns of data in a single picker component. The reason I have chosen to do this within 1 component is that I want the arrays to scroll together, which I can't get multiple components to do.
The trouble is, I can't get this way to work either, as titleForRow and viewForRow will only return one value (as per the rules of C). I tried making them output arrays and dicts but that caused data type errors.
I can get it to work just fine using 1 component, 1 array with viewForRow but that only allows justification the whole field, not parts of the string.
The below code works great and gives a correct answer with return label2; and if changed to return label1 is correct also , How do I get both to display?
- (UIView *)pickerView:(UIPickerView *)pickerView viewForRow:(NSInteger)row forComponent:(NSInteger)component reusingView:(UIView *)view
{
UILabel *label1;
{
label1 = [[UILabel alloc] initWithFrame:CGRectMake(10.0f, 150.0f, 130.0f, 60.0f)];
label1.textAlignment = NSTextAlignmentLeft;
label1.text = [_firstList objectAtIndex:row];
}
UILabel *label2;
{
label2 = [[UILabel alloc] initWithFrame:CGRectMake(100.0f, 10.0f, 175.0f, 100.0f)];
label2.textAlignment = NSTextAlignmentCenter;
label2.text = [_secondList objectAtIndex:row];
}
return label2;
}

Answer 1

Setup your UIPickerView to have one component.
Now assuming that your two array _firstList and _secondList have the same number of objects in them, you have two options:
Use the simple pickerView:titleForRow:forComponent: method to return a single string build from the two values:
- (NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component {
return [NSString stringWithFormat:#"%# - %#", _firstList[row], _secondList[row]];
}
Of course you can format the two strings as needed. This is one example.
Use pickerView:viewForRow:forComponent:reusingView: like you tried but return a single view that has two labels added to it.
- (UIView *)pickerView:(UIPickerView *)pickerView viewForRow:(NSInteger)row forComponent:(NSInteger)component reusingView:(UIView *)view {
UILabel *label1;
UILabel *label2;
if (view) {
label1 = (UILabel *)[view viewWithTag:1];
label1 = (UILabel *)[view viewWithTag:2];
} else {
view = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 320, 40)];
UILabel *label1 = [[UILabel alloc] initWithFrame:CGRectMake(10.0f, 0.0f, 130.0f, 40.0f)];
label1.tag = 1;
label1.textAlignment = NSTextAlignmentLeft;
UILabel *label2 = [[UILabel alloc] initWithFrame:CGRectMake(100.0f, 0.0f, 175.0f, 40.0f)];
label2.tag = 2;
label2.textAlignment = NSTextAlignmentCenter;
[view addSubview:label1];
[view addSubview:label2];
}
label1.text = _firstList[row];
label2.text = _secondList[row];
return view;
}
Note how this properly makes use of the reused view.