Swap two pickerviews - ios

Question

I'm currently working on my first "big" project. The project is a simpel converter for different currencies. I wonder if it is possible to in some way invert the two arrays. I don't know how I should implement the if statement. Becouse if i put it in the title for row method i'm will probably get the control may reach non-void error message. I may explain this pretty bad but i just started programming.
if(!reverse) { // do nothing } else {
// swap the two pickerviews
}
//Toggle reverse on/off <->
- (IBAction)Reverse:(id)sender {
reverse = (reverse+1)%2;
NSLog(#"%d",reverse);
}
//what title for row
-(NSString*)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component {
if (component == 0) {
return [Datarray objectAtIndex:row];
}
return [Datarray2 objectAtIndex:row];
}

Answer 1

I see what you're trying to do. Instead of having two or multiple PickerViews. Just change the DataSource and reload the PickerView. if you only have two currencies just use a flag, otherwise create a NS_ENUM to identify which array the PickerView DataSource should use and in the DataSource methods like, pickerView:titleForRow:forComponent: use a switch case of if-else statements to identify the correct dataSource array.
// .h file
typedef NS_ENUM (NSInteger, CURRENCY_TYPE) {
CURRENCY_TYPE_US,
CURRENCY_TYPE_DK
};
#property (nonatomic, strong) NSArray *dataArrayUS; // In this example, these arrays contains NSStrings
#property (nonatomic, strong) NSArray *dataArrayDK;
#property (nonatomic) CURRENCY_TYPE currencyType;
// .m file
-(NSString*)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component
{
switch (self.currencyType) {
case CURRENCY_TYPE_US:
return self.dataArrayUS[row];
break;
case CURRENCY_TYPE_DK:
return self.dataArrayDK[row];
break;
}
}
- (IBAction)currencyChangingAction:(id)sender
{
// Add some logic that changes to the self.currencyType to the correct currency.
self.currencyType = CURRENCY_TYPE_US; // or _DK
// And Reload Picker
}
EDITED:
Is this what you want? - This will only work if you have two Arrays though.
//what title for row
- (NSString *) pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component
{
return (component == 0) ? [Datarray objectAtIndex:row] : [Datarray2 objectAtIndex:row];
}