How do you save the value of a UIPickerView as a string? - ios

Question

I am trying to save the selection in a UIPickerView as a string, but I seem to be losing the value after I dismiss the view. How can I retain this value?
.m file
/*********************************/
#pragma mark -
#pragma mark PickerView DataSource
//Below are the functions for the UIPicker:
- (NSInteger)numberOfComponentsInPickerView:
(UIPickerView *)pickerView
{
return 1;
}
//count of categories array denotes how many elements the picker will have
- (NSInteger)pickerView:(UIPickerView *)pickerView
numberOfRowsInComponent:(NSInteger)component
{
return arrCategorySelection.count;
}
//return the corresponding caregory
- (NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component
{
return arrCategorySelection[row];
}
/*********************************/
#pragma mark -
#pragma mark PickerView Delegate
//Delegate method for the category picker
-(void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component
{
//trying to save the value as a string
selectedCategory = [arrCategorySelection objectAtIndex:row];
}
.h
#property (nonatomic, retain) NSString *selectedCategory;

Answer 1

A property is tied directly to the controller that it is declared in. To use the property, you need to access it before the controller is dismissed, normally with a delegate call. Apple has lots of example code on how to do this. Below is a summary.
Let's say MasterView is presenting PickerView. Normally, you want to do this with a segue.
[self performSegueWithIdentifier:#"Present PickerView" sender:nil];
In PickerView.h you declare a protocol before the #interface portion:
#protocol PickerViewDelegate <NSObject>
-(void)itemSelected:(NSString*)item;
#end
Then in the #interface portion, you declare a delegate property
#property(weak)id<PickerViewDelegate> delegate;
In MasterView, you need to populate this delegate in your prepareForSegue method
-(void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
if ([segue.identifier isEqualToString:#"Present PickerView"]) {
PickerView *controller = segue.destinationViewController;
controller.delegate = self;
}
}
You also need to implement the delegate method (remember, it is best practice for the MasterView to both present and dismiss PickerView)
-(void)itemSelected:(NSString*)item {
// do something with item
[self dismissViewControllerAnimated:YES completion:nil];
// depending on the presentation, you may need this instead
// [self.navigationController popViewControllerAnimated:YES];
}
Now in PickerView.m, establish some way for the user to say he is done with his selection, say a tap of the save button on the upper right that calls this method:
-(IBAction)saveButtonTapped:(id)sender {
if (self.delegate && [self.delegate respondsToSelector:#selector(itemSelected:)]) {
[self.delegate itemSelected:self.selectedCategory];
}