How to get location of an object relative to the Window in iOS?

Question

How do we get the "visual" coordinates of an object? For example, getting the frame of a textfield within a UIScrollView will give me the X and Y relative to the UIScrollView, but I want to know the X and Y as if they were shown in the view.

Is there a built in function?

Answer 1

Once you have the point as a CGPoint you can call:

// Objective-C
- (CGPoint)convertPoint:(CGPoint)point toView:(UIView *)view

// C#'s UIView class contains this method:
PointF ConvertPointToView (PointF point, UIView target);

on you UIView.

pass in you point in your views co-ordinates as point. And for view pass in

// Objective-C
[UIWindow keyWindow]

// C#
UIWindow.KeyWindow

This will then return a CGPoint (PointF in C#) converted into the windows coordinate system!

So for example:

// Objective-C
CGPoint convertedPoint = [myScrollView convertPoint:textField.frame.origin 
                                             toView:[UIWindow keyWindow]];

// C#
var convertedPoint = myScrollView.ConvertPointToView (
     textField.Frame.Location, UIWindow.KeyWindow);

Hope this helps :)

Answer 2

UIView has some convertPoint and convertRect functions:

• - convertPoint:fromView: <--link to Apple doc
• - convertPoint:toView:
• – convertRect:toView:

etc.

Answer 3

Might just be me, but wouldnt this work fine?

- (CGRect) convertView:(UIView*)view
{
    CGRect rect = view.frame;

    while(view.superview)
    {
        view = view.superview;
        rect.origin.x += view.frame.origin.x;
        rect.origin.y += view.frame.origin.y;
    }

    return rect;

}