I'm creating a project in Swift that draws some shapes, based on this tutorial. My project involves some things to most, like removing the shape drawn on the View.
To begin need to recognize them in layers, or uniquely identify what form should remove.
I'm working on it just over two weeks, but I'm running out of idea what to do.
My question:
How can I identify and separate shapes drawn with Core Graphics in Swift?
I found the way:
for layer in self.view.layer.sublayers! {
print(layer)
}
I can get all layers drawing in my view.
Related
I want to Draw lines from one object to another object. Like a Matching object game. I want Swift language with UIKit Use. Here I attach the Sample Screenshot.
Does anyone have experience with this? then please help me.
You have a couple of choices.
You can create a custom subclass of UIView that implements the draw(_:) function to draw custom content. That view would need to big enough to enclose all of your custom drawing. You'd fill most of the view with clear, and then draw the lines you want using Core Graphics.
The other option is to use Core Animation layers. You could add a CAShapeLayer to your view's layer, set up the shape layer with the desired line thickness and color, and add a path to the layer containing the lines you want to draw. (Note that if you use CAShapeLayers, all the lines drawn in a single shape layer will be the same color. You'll need multiple shape layers in order to draw in multiple colors.)
Both approaches will require some research. Shape layers are more efficient and take better advantage of the graphics hardware on iOS devices, but using them has a fairly steep learning curve.
You should be able to google examples of both approaches. Try search phrases like "Custom drawing in a UIView" and "drawing with CAShapeLayer". I wrote a little demo app called OvalView that demonstrates how to create a UIView subclass that manages a shape layer.
Edit:
I adapted the code from my sample app into a demo called LinesBetweenViews. The new demo has a custom UIView that draws lines between any pairs of subviews you put into it.
Here is a screenshot of the demo:
If you answer my questions I can upload the demo app to Github so you can look at it.
Edit #2
See this Github repo for a sample project that draws lines between pairs of subviews.
I am creating an Application that contains multiple Images all stacked together. The Application moves those Images frequently, so I am trying to pack them into one big container. Moving this container (of course) causes the Application to lag.
I have tried packing mutiple UIImageViews into one UIView (not a good idea) and packing multiple CALayers with an Image on each one into one big CALayer (still not really helpfull).
So what I am looking for is an option to stick multiple Images (like a puzzle) into one CALayer. I don´t need to reposition those images, since I am just moving the main Layer.
Thanks for any help!
well, one easy way would be to draw them yourself:
have your own custom subclass of CALayer and implement drawContext
set needsDisplayOnBoundsChange so you tell CA that you need to draw stuff yourself
I am new to iOS platform and i heard about MVC archtecture.
To draw a circle i just create a separate UIView class and override the drawRect: and able to do this.
But now i want to rebuild the same project using MVC architecture.The main aim is to separate my Model part from View & Controller part.So that i can extend my project.
So how can i do this?
Any sample application for reference?
I'm not sure what you want to separate. Drawing a circle would generally fit into the "View" part of the MVC architecture, which is what you have already done. Code that would, for instance, change the colour of the circle would live in the "Controller" part, which on iOS is a UIViewController. If you had something storing information on what the circle looked like (i.e. size, colour, etc.), that could be considered part of the model, and can be stored in its own class, pulled in by the view controller and passed to the view when it is neede.
Here is a link that may help.
http://www.bit-101.com/blog/?p=1969
As for the model side of things, Core Data is a technology that can help.
http://developer.apple.com/library/ios/#documentation/Cocoa/Conceptual/CoreData/cdProgrammingGuide.html#//apple_ref/doc/uid/TP40001075
The separation would be the drawing code in drawRect and the size and location in a model with a controller getting the circle attributes from the model and requesting the drawing and passing the attributes to the view. The model might be another class or an API supplied class such as an NSDictionary.
By creating a separate model if there were multiple circles the controller could make multiple draw requests, one per model circle. Or there could be multiple views that the circle(s) would be drawn in or different representations such as a text list of the circles attributed in one view and graphic circles in another.
Many patterns seem trivial and not particularly useful in the trivial case yet in a real-world program work very well.
I am new to iPhone development and am currently toying with recreating a charting tool I developed for Silverlight.
Currently I'm using a gradient to 'fill' a rectangle representing a bar within a chart. Is it possible to animate this gradient so it changes colour when a user touches the bar within the chart.
I have looked through the Core Animation guides provided by Apple but cannot see a property which targets gradients. I suppose I could use a transition to fade between two rects, one of which has my starting gradient and the second with the 'touched' version but this would mean obviously drawing multiple rect objects for each bar with I assume extra performace overheads.
Any ideas?
Yes, indeed you can animated gradients with Core Animation.
The CAGradientLayer class that came out in 3.0 has a nice API for rendering gradients into a layer and animating color and color-stop changes as well.
I did a post on this class a little while back, along with some sample code that's linked at the bottom.
In the sample I animate the gradient by building a CABasicAnimation, but you can implicitly animate the change as well, by just passing a new array of colors to the gradient layer's colors property. Use implicit animations unless you have a reason not to.
Check that out and let me know if you have any questions specific to the UI you're trying to animate.
This might be trivial for some of you, but I have two screenshots from the Lose It! app in which I'm curious how two different screens were put together.
The first:
That middle graph which shows the statistics chart. Is that a custom image being drawn on top of with Core Graphics / Quartz to achieve the desired numbers? Is the yellow line that's being dynamically allocated all the work of Quartz?
And second:
This one might be a bit easier, but the whole bar which looks like a native UIKit widget, which contains [Budget, Food, Exercise, Net, Under]. There appears to be a drop shadow above it. Are they doing a drop shadow on the UINavigationBar? Is the menu below it just a UIImage that a designer was able to craft to look like the UINavigationBar?
If there's a blog out there which teaches UI tricks such as these, I'd love to read more.
1) Yes, it's likely a view that uses the chart as a background and then uses core graphics to render the line,
2) This could be a single view divided into four sections. Each section has two lines of text drawn with different colors. It's possible that each section may be a view that encapsulates this behavior.
I'm not aware of any blog that teaches these "tricks". It's really a case of understanding what functionality is available and then using it creatively to develop your UI.
For example we know it's possible to;
Draw images at different sizes/positions.
Draw text in different fonts, sizes, colors, alignment
Draw primitives
Really, when you have those you can create pretty much anything.
I think there's an SDK sample that demonstrates using custom views to create a fancy timezone style applications. That might be one worth checking out.
Update: found it, it's here.