use two UIPickerView in the same class - iphone

Question

I wrote this code for the first UIPickerView
- (void)viewDidLoad
NSURL *url = [NSURL URLWithString:
#"http://localhost:8080/Data/resources/converter.country/"];
ASIHTTPRequest *request = [ASIHTTPRequest requestWithURL:url];
[request setDelegate:self];
[request startAsynchronous];
// countrys = [[UIPickerView alloc] init];
countrys.delegate = self;
countrys.dataSource = self;
countrys.showsSelectionIndicator = YES;
countryField.inputView=countrys;
- (NSString*)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component {
NSString *codeCity;
codeCity=[countriesArray objectAtIndex:row];
return codeCity;
}
- (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView {
return 1;
}
- (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component {
return [countriesCodeArray count];
}
And then i wanted to make another UIPickerView with cities . I wrote this
citys.delegate = self;
citys.dataSource = self;
citys.showsSelectionIndicator = YES;
cityField.inputView=citys;
But when i click on it i have countries list . How should i change the datasource ? And how to use the default function of the UIPickerView, like numberOfComponentsInPickerView , numberOfRowsInComponent: ... with the second UIPickerView ?

Answer 1

You can assign tag to your pickerviews and then can check these tags in datasource/delegate methods
citysPickerview.tag = 2
otherPickerview.tag = 1
// then you can check for these tags in pickerview datasource/delegate methods like this -
- (NSString*)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component {
NSString *title;
if (pickerview.tag == 1) // this is otherPickerview
{
title=[countriesArray objectAtIndex:row]; // your logic to get title for otherpickerview
}
else if (pickerview.tag == 2) // this is citysPickerview
{
title=[countriesArray objectAtIndex:row]; // your logic to get title for cityspickerview
}
return title;
}
You should follow this same mechanism in your all datasource/delegate code :)

Answer 2

What you could do is set tag for the 2 UIPickerView, like so - [countryPicker setTag:1], use these tags to distinguish between the 2 picker views.
- (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView
{
return 1;
}
- (NSInteger)pickerView:(UIPickerView *)pickerView
numberOfRowsInComponent:(NSInteger)component
{
if([pickerView tag] == 1)
return [countryNames count];
else
return [cityNames count];
}
- (NSString *)pickerView:(UIPickerView *)pickerView
titleForRow:(NSInteger)row
forComponent:(NSInteger)component
{
if([pickerView tag] == 1)
return [countryNames objectAtIndex:row];
else
return [cityNames count];
}

Answer 3

For a simpler solution, just compare the pickerView pointer. That way you save the additional complexity and maintenance of using tags.
- (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component
{
NSInteger numberOfRows = 0;
if (pickerView == countrys) {
numberOfRows = [countriesCodeArray count];
}
else if (pickerView == citys) {
numberOfRows = [citysCodeArray count];
}
return numberOfRows;
}
Note: This answer is based on giuseppe's comment.