I need to continuously change the color of all the lines I draw in a UIView. And I drew all the lines within the drawrect method to assign colors. Now I need to animation and change the colors as long as the view is shown. Is there a way to do it? Thanks a lot!
Look into using one instance of CAShapeLayer for each of the lines, instead of drawing them in drawRect:. You can animate changes to each layer's path and strokeColor properties as necessary.
EDIT
If you're just drawing horizontal lines, you may be better off simply using a UIView for each. Set the backgroundColor instead of implementing drawRect:. You can animate both the frame property and the backgroundColor property using +[UIView animateWithDuration:animations:] (or the more powerful variants of it). This is generally simpler than messing around with Core Animation.
Live and learn. Animations are better done outside of -drawRect:
Change your "lines" to individual UIView instances added as (preferably opaque) subviews to your view. You'd then set the appropriate backgroundColor on the view.
You can then use a simple UIView animation to animate them.
Related
So basically i have two image objects, 1 portrays a line and the other a circle. I wanted to know if its possible using something like CABasicAnimation to loop the line image across the x axis but still keeping it within the circle image?
Yes, you should be able to do this with either CABasicAnimation or UIView animation.
CAAnimations only operate on CALayers, and they are rather tricky to use. I suggest using UIView animations on UIImageViews or other UIViews instead. You could even set up a custom subclass of UIView to have a CAShapeLayer as it's backing layer and then animate the custom UIView using UIVIew animations
I wonder what the best way to create a horizontal line is?
I have a few labels / text and I would like to add a horizontal line between them. More or less like a when using twitter bootstrap.
Right now I am using a UIview and setting it as 1 in height with a black background color. But I guess this isnt the best way to do it?
That is the way to do it in iOS. UIView is the class which represent something to be shown on the screen. Every UI component is direct or indirect descendant of UIView. So, you should use UIView.
UIView is backed by CALayer to render the content to screen. You could also use CALayer, CAShapeLayer or other layer classes to create a border. But, I would not recommend to use CALayer just to show a border as it is simpler to use UIView with height of 1, on the top of that, you get some nice addition such as autolayout. If you use CALayer, you will have to set frame to layer at appropriate time when the view bounds change. It could also be tricky due to some intrinsic animation within CALayer.
I am trying to create a view to implicate a swiping feature in a table view like the picture below.
I just want to curve one side of a view in equally to imply a swiping gesture. Is this easy to do in code? Or is it better to mask an image over the view? Please suggest.
Subclass UIView, implement the drawRect: method and do that shape (either by drawing to the context, or by using a bezierPath).
Make sure you set the view to opaque, and the backgroundColor to clearColor.
I have a UIView subclass object that animates and therefore changes its position over time as a subview in my UIViewController's view. Actually my moving UIView subclass is just an image of a ball and it's moving as if it was hanging down from my devices screens top border. But to be a real pendulum I'd like to also draw a line between my ball and the CGPoint it hangs down from on top of my screen.
My idea was to just draw a line every time the UIView changes its position. But as the moving is done within an iOS API (I'm just calling something like [myBallView swing]) I can't do this at the same place the movement is happening. I'm actually not animating the view myself.
The only solution I have in my mind to solve my issue is pretty bad: subclassing UIView, adding it as a superview to my moving UIView and adding a line every time drawRect is called. But I'm not even sure drawRect is going to be called there. Either way, there must be a better solution for this.
Does anyone know a good solution to my problem?
Making a custom subclass of UIView as the superview is reasonable.
However, rather than drawing the line yourself, I would suggest implementing +layerClass in your custom view, and making the backing layer a CAShapeLayer.
Then you can create a CGPath in the view's shape layer that is a line, and manipulate the start and end points of the line when your other view's center moves. Shape layers are designed to draw as part of the screen update process, and you could even make the change animate by changing the endpoints of the path with a CABasicAnimation.
I have a UIView that I draw a CGPath to and would like to draw an overlay onto the entire view itself, one z level above the rendered CGPath.
How is this done? Should I use a layer? I would like to draw or fill parts of the view repeatedly, so I am not sure if it might be better to use some kind of fill method. Is there a more efficient way to fill parts of the view other than drawing a new path?
I want to create the effect similar to a progress bar, extending the overlays width during runtime depending on a value.
You could use a subview (or, similarly, a sub-layer) for this. A subview of a view will appear above the content rendered in drawRect:.
If you can get away with using a UIImage background (say, one created with resizableImageWithCapInsets:), and simply changing the size of that view over time, it will likely be more efficient than redrawing in drawRect:.