I am working on iPhone application development and have come across shadows of UIView.
I know how to show shadows to a UIView but what I am actually interested in is to drop shadow inside the UIView.
Like when I set shadow properties of a UIView the shadow is dropped behind the view. I want it to come over the view so that the view looks as if it is pressed inside.
Example of such view is UITextField with roundedRect styling.
Thanks,
It depends a lot on the final effect you want to achieve.
The easies way would be a custom image with a prebacked shadow as background. This will give the illusion of a recession in the surface of the view. You can then add subviews to it as usual.
Alternatively, you can override the drawRect: method and draw the view as you like there, "inverted drop shadow" included.
Related
This tutorial shows how to draw on a graphics context for the view using Quartz 2D:
http://www.techotopia.com/index.php/An_iPhone_Graphics_Drawing_Tutorial_using_Quartz_2D
But I want to draw on a UIButton, not on a view. How can I do that?
Thanks
Draw on UIView . Add the view as subview to your UIButton.
A button IS a UIView. It inherits from UIControl, which inherits from UIView.
So buttons have a drawRect method.
So you can do everything described in the article you linked on a button.
However, buttons are set up to do a lot of things for you, and overriding the drawRect method could make those things not work correctly.
Buttons normally draw a title and a rounded rectangle frame. You can turn that off by setting the button's type to custom.
Custom buttons will draw an image if you install one.
Buttons normally also either draw a highlight over their image, or have a second image to use for the highlighted state. If you want to implement drawRect, you'll need to handle drawing the highlighted state yourself.
In general, you want to avoid using drawRect and use some other technique to get the content you want into your views.
What, exactly, are you trying to do?
I'd like to have a UIView where the user can select each of the four corners and stretch the view by independently moving them.
How would I implement such a view?
To do this, you will need to subclass UIView and handle touch events manually. When you get a touch event, you will have to do some math and then set the frame of the view to the new size. I'd recommend making the background image a stretchable image using stretchableImageWithLeftCap:topCap. It shouldn't actually be that hard.
So I made a UIView subclass let's called it 'MyView' that simply draws a line inside the DrawRect method.
I then drag a UIImageView in interface builder and put it inside MyView. But now when I run the program it's obscuring the line that I'm drawing. I'm wondering, is there a way for me to draw the line on top of the image that I have dragged into my View?
No, you'll have to reorganise the view hierarchy. CoreGraphics uses a painters model so views behind will always be drawn over by views infront. To solve this you could use a container view that holds your image view and has a transparent view (line drawing view) that sits over the image view.
Another option is to draw the image using core graphics calls in your drawRect method and then draw the line over it.
One way is to have whatever adds MyView to add your UIImageView on top of MyView. It's not ideal (you probably have good reasons for keeping MyView and the UIImageView in a single class) but definitely solves your problem (I recently did this, only, I added it to the keyWindow =)
I would use a CAShapeLayer that has a path representing the line, and insert that layer ahead of the built-in view layer. Then it should draw on top.
I have a UIView which contains a zoomable UIImageView and also another semitransparent UIView on top of that.
What I am trying to achieve is to be able to zoom the UIImageView while keeping the semitransparent view static and not zoomed.
If I add the semitransparent UIView on top of the UIImageView (which is added to the UIScrollView), everything zooms. However, if I add both as subviews to the base UIView, the touches only get tracked is the semitransparent UIView since its the last one added.
I do need control to reside first at the semitransparent UIView for the touches since I may want to resize the semitransparent view. However, I'd like to pass control of the touches to the UIScrollView if two fingers are used. Is there anyway for me to achieve this? The nextresponder doesn't seem to work. I also tried to use hittest in addition to subclassing UIWindow, but the base UIView needs to push/pop navigation controlling ability so I don't think I can subclass UIWindow to push onto the navigation stack.
Any help would be appreciated.
Thanks,
Winston
Hm.. you can try this hierarchy (possibly subclasses):
UIView (container)
> UIView (semitransparent overlay)
> UIScrollview
- UIView (zoomable content)
Like this, the overlay does not scale.
The tricky thing then is the user interaction on multiple layers. Its easy if there are areas in your overlay that should not detect user touches, for that you just set the UIView property 'userInteractionEnabled' to 'NO' for the view parts where touches should be 'forwarded' to the underlaying layers.
But if I get you right, you need something more complicated. You probably could set up some kind of master-touch-controller in the container UIView, that finds out what is happening and then calls certain methods of its subviews / forwards the events.
I don't know all the exact methods you need to override/implement in the container, but check out the tapZoom demo from the ScrollView Suite sample code. It's a pretty nice example there.
Just out of curiosity, may I ask what this interaction model is used for?
I've created a NIB file with some button controls on it, and as a background it has an ImageView which contains a PNG file loaded from my project.
What I want to do is to draw on top of the ImageView - imagine that my UI is a clockface and I want to draw the hands of the clock on top of the background image.
Is it the correct approach to try to subclass the UIImageView and use its DrawRect as when I use the DrawRect of the default view I don't see anything on the screen?
I'm a little lost as I'm finding this particular bit of the documentation hard to follow.
Thanks.
Create a new custom UIView (e.g. named HandsView) that sits on top of your background view (by adding it as a subview of the UIImageView). In the custom view, you can use the drawRect method. Make sure, you clear the context to transparent, so that the background image can be seen below the HandsView.
If you just want to draw turning hands, you can also try to use two fixed UIImageViews with the images of the hands and use the transform property to apply a rotation.