Can i define UIView as a variable in Objective-C?

Question

According to documents i read, they always show that I should define a subview in a class. Like this : @interface PolygonView : UIView. I have to inherit from UIView.

Could i define a variable with UIView type in a class which inherit from NSObject? After that, i make a connection from that variable to UIView which is defined in Interface Builder. The problem is that i can not override - (void)drawRect:(CGRect)rect

Answer 1

Generally you'll do something like this

@interface MyView : UIView {
// Declare IBOutlets here if you wish or other instance variables you may need
}
@end

@implementation MyView

- (void)drawRect:(CGRect)rect {
// Drawing stuff
}

And then in Interface Builder, create a view (usually by making a View XIB or by dragging out a Custom UIView object onto (well, into) another UIView in the XIB thus making it a subview) and then in the Inspector pane, set its Class to be MyView. Then you can connect any IBOutlets you've defined in the MyView interface declaration.

Answer 2

Yes, you can define a variable in a plain NSObject subclass that points to a UIView. But if you do, of course you can't override drawRect: — that object just has a reference to a UIView, it isn't a view itself. It's much like you can have a variable that's an int, but that doesn't mean the object containing that variable is an int.

If you want to override a view's drawing, you need to make a view. You can still have a separate class that interacts with your UIView subclass from outside.