UIPickerView with empty arrays - iphone

Question

I've set up a UIPickerView successfully, but I'm wondering about the best way to handle the case when the data is initially empty. For my current iteration I use the following code for the pickerdelegate
-(NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component
{
if ([flash_cards count])
{
return [[flash_cards allKeys] objectAtIndex:row];
}
return #"";
}
where
flash_cards = NSMutableDictionary *
Whenever I try to scroll it creates an error of indexoutofbounds which is only logical. How do I handle the case of an empty array?
EDIT:
Also as part of the code I implemented the following
- (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponen: (NSInteger)component
{
return [flash_cards count];
}
#pragma mark Picker Data Source Methods
- (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView
{
return 1;
}

Answer 1

To solve this problem you should return 1 instead 0 in the method numberOfRowsInComponent from the UIPickerViewDataSource when the array is empty, like the example below:
- (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component
{
return [self.myArray count] == 0 ? 1 : [self.myArray count];
}

Answer 2

You should also implement the UIPickerViewDataSource methods:
- (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView
- (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component
You can still use flash_cards (or [flash_cards count]) to derive the return values of these methods; if your data is empty, you can return 0, then later call -reloadAllComponents on your picker view when you get data loaded.