iphone: mechanical drawing & layers -

I need to do some mechanical drawing. I can (1) display the image of the part,

< P> [self.view addSubview: thePartAsImageView];

(2) Apply two sliders (for the width of a horizontal portion and the height of a vertical portion),

heightSlider.transform = CGAffineTransformRotate (heightSlider.transform, 270.0 / 180 * M_PI);

(3) Displays the respective values ​​(dimensions) as the user moves the slider, and even how (4) the dimension with the arrow borders:

CGContextAddLineToPoint

Can not I do it (5) I remove them after removing those rows.

Do I want to "if userTouchedTheHorizontalControl then eraseTheLinesForTheVerticalControl."

If I understand correctly - first, quartz everything that composites for a layer, and second, that only work on CALayer, GeekGameBoard and so on Mac - so I have to do something different but there is something Can I open the GL other than the switch?

After "text" itemprop = "text">

You can look at Multitatch - on an iPhone, everyone can change the size of an image With two fingers pinch or extension is expected - this is the same in the map, photo, everywhere. By doing this the other way your application will look weird.

How about background [UIColor clearColor] and opaque on top of everything with a new UIView drawing about its dimension lines = No, then that scene Removal When Lines Are Not Required?