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.
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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.
Question: How do I display a background image underneath a CGContext?
I have created a view controller using the storyboard and placed a view with a full-screen background image. Then, using the same view controller, I created a outlet to a UIView that has a CGContext where I draw a few lines.
Everything works except that the drawing takes place underneath the background image. (Suddenly I wonder if it's not the CGContext but the UIView that is the problem.)
I found a similar question here, but the solution makes it sound like the background image has to be constantly refreshed using CGContextDrawImage with a CGImageRef. Which may be true, but a static image being constantly refreshed doesn't sound like a very elegant solution. Thank you!
Create custom UIImageView subclass where you will draw your custom background.
Better to subclass UIImageView instead of UIView, because in this case you don't get problems with adding other views above this in Interface Builder.
Add UIImageView to your view controller, and change class to your custom class. Add all other views above.
Question: How do I display a background image underneath a CGContext?
Answer: Set the color of the view with the CGContext to Clear Color.
That way the background image is visible as well as the lines that are subsequently drawn. Guess I kind of overcomplicated that one.
Thank you for the response Vitaliy.
I created a container view that holds a bunch of child views - a collection view, a custom toolbar and some bits and pieces.
The design has a border on the top, left and right sides, but not the bottom, so I overrode drawRect to include border.
When I added the toolbar I noticed that it appears over the top of the border. (For some reason I initially thought it wouldn't but of course it does!).
Is there anyway I can tell drawRect to draw over the top of my subviews?
Of course there's loads of other ways to solve my problem (adjust the toolbar's frame for example) however I'm asking this question in order to get a deep understanding of how drawing works in relation to compositing and the view hierarchy.
Drawing happens beneath all subviews of a UIView. Think of it as being on the very base - an actual part of your view - and then each subview is added on top of your view. To make the drawing above the subviews is the same as wanting for the subviews to appear under the view, while still being subviews. Perhaps that analogy makes it clearer why it must always be on the bottom. And it also leads you logically to the solution:
To get the drawing to appear above subviews, simply create a new UIView subclass to place the drawing code inside, and place this above all other subviews.
It might also be a good idea to override your UIView's addSubview: implementation, to ensure your subview always remains on top.
I believe you can't, since the drawRect is called first for the view and when it has finished drawing drawRect is called for subviews to draw over it. Maybe just make another subview on top of that view that has the borders you need and is transparent everywhere else?
Subviews are drawn on top of their super views. So the answer to your question is no.
At the time when you draw the border on your container view, Cocoa hasn't even started drawing the toolbar yet.
I guess you could make the top of the border a subview or move the toolbar down a bit.
There are a lot of questions about how to draw a drop shadow for a view. But how can I have my view cast a shadow that is received only by one other view?
If view A is the view with the shadow and view B is the parent of A, you can set masksToBounds which is a property of B's layer to YES.
Contents of B and its subviews will not be shown outside of B. They will be clipped.
More detail here: What UIView layer.masksToBounds is doing if set to YES?
However, if you want the shadow drops on more complex scene, you might need to be a little more specific.
Make an app with a white background.
Make your view plus shadow.
Take a screen shot.
Use the screen shot in your original app.
Of course you could also make the picture on the fly in code, but that is a bit more challenging. In any case, it would be code you do not need in your final app.
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:.