Question

If I have an protocol (say UIPickerViewDataSource) and I implement its required methods, do I need to declare those methods in the header file of my class?

At the moment I’m not doing so and I get a warning of incomplete implementation (although everything works fine). If I do add the required methods in the then I don’t get such warning:

- (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView;
- (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component;

Is this the correct behaviour? Is it really necessary to add the declaration for required protocol methods in the header file of my class?

Answer 1

No, you don’t. Declaring that the class implements that protocol and implementing the methods is enough. You could still declare them in the header for documentation purposes, though.