Find when picker view selection changes?

Is there any way I can have an object receive a mes开发者_运维问答sage when the user changes the selected row in the picker view? My pickerview has two components and it is dismissed when the user taps the screen once. But I need to gray out certain options in the second component depending on which option in the first component is chosen.

One other option is to use a timed function to periodically check which row is selected, but that's really hacky. Are there any delegate functions I can use?

Use - (void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component.

row tells you what row it is and component tells you which component it's in.

Remember to include <UIPickerViewDelegate> in your header file.

UIPickerView has a delegate that you can use, called UIPickerViewDelegate. In it, there is a method called:

- (void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component

That lets you know what row they've selected and in what component, and should accomplish what you're asking, if I understood correctly.

What about:

- (void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent

It's one of UIPickerView's delegates.

You might want to have a look at the UIPickerViewDelegate Protocol

Especially the message might be interesting to you:

pickerView:didSelectRow:inComponent: Called by the picker view when the user selects a row in a component.