Question

I’m learning to develop apps for Iphone. I follow a book by Apress which I find very useful. But as nothing is perfect some issues are not well described and just skipped.In one of the applications I have to assign five images to each of the five components of a pickerview. But my question is why do/can not we use an instance of UImage itself but UIImageView to display on the picker.

Answer 1

As in above question you are asking why we can not use UIImage instead of UIImageView as component for UIPickerView.

UIImage is subclass of NSObject class, If we talk in terms of M-V-C its a M(model). and model in itself is nothing until its used.

UIImageView on the other hand is subclass of UIView which stands for V(view) in M-V-C so it uses your model for its contents.

So, they are two different things, not alternate. Also, if you go through UIPickerView‘s class documentation then you will find that it has method

- (UIView *)viewForRow:(NSInteger)row forComponent:(NSInteger)component

that configures view for specified row component. so it meanse we need view(UIImageView) and not the model class(UIImage). here for component you can return subclass of UIView.

Please refer apple’s documentation.

Thanks,