I'm building an iOS application that will be drawing diagrams for the user to see and manipulate (move, add, remove elements) and I'm having trouble choosing how to implement the actual rendering.
I find the default cocoa-touch controls to be too limited for this purpose yet graphics frameworks such as Quartz/OpenGL ES/Cocos2D seem a bit overkill.
Can anyone suggest an approach to this situation or perhaps a library better suited to my needs?
Thank you.
You can have each drawn object (box, association) be a custom UIView subclass added as a separate subview of your main view. Each subview can catch events from finger touches.
Apple's Touches sample code shows how to receive events on subviews and move them in response to dragging motions.
Related
If you go to Apple Photos and do pinch zoom you can zoom in/out to change the number of columns in the grid. I assume it uses UICollectionView, however, I have no idea how it obtains this animation.
It's not difficult to change the number of columns in UICollectionView programmatically, I don't quite get the animation.
Any ideas?
It looks like the gesture triggers a new layout. There's a whole class dedicated to switching between layouts gracefully: UICollectionViewTransitionLayout. The docs say in part:
You can use UICollectionViewTransitionLayout as-is or subclass it to
provide specialized behavior for your app. A common use for transition
layouts is to create interactive transitions, such as those that are
driven by gesture recognizers or touch events.
Unlike a regular time-based animation, the transition between layouts is driven by a transitionProgress property that you update, so the transition can easily track a gesture. You can see exactly that kind of thing happening in Photos: if you alternate between pinching and zooming, the transition tracks that by going back and forth.
It's possible, perhaps likely, that Photos uses a subclass of UICollectionViewTransitionLayout in order to provide a more polished user experience, but if you're looking to emulate what Photos does, I think this class is the right way to start.
All you ios architects out there, please help me choose architecture/technology for the following iphone/ipad app.
The app itself is a financial app, but we want more of a game look-and-feel of the app, so we probably don't want to use the builtin looks of the cocoa widgets. The elements on the screen will probably be some kind of blob-shaped images.
The app will essentially have five "blob"-shaped areas, spread out evenly across the screen. One of the blobs will be centered and larger than the other ones. Within each blob there will be clickable areas which will pop up "details" and menu-action blobs. These blobs are also graphics objects and must not take over the whole screen. The blobs should animate nicely when popping up. The graphics elements will have a couple of lines of text, which are generated, so the overlaying text itself cannot be part of the static background-image.
The main user interaction will be swiping within the center blob, displaying summaries of the items that are conceptually contained within the blobs underlying data store. Now and then, the user will drag and drop the item to one of the other blobs. While dragging, the item should be traced by a line and when dropping on the other blob, the item should be animated to look like it's being "sucked into" the blob.
Now, what kind of technique would you suggest for this app? Is Cocoa suitable in this scenario? Should I use a game framework like Cocos2D? All kinds of suggestions including example code snippets are most welcome.
I realize that this question might not be as straightforward and to the point as questions generally are on SO, but I hope your answers will come to use by more people than me. Thanks!
EDIT (MY SOLUTION):
I eventually ended up doing everything in UIKit, which was a lot easier than I expected.
Briefly described I used UIButtons with Custom style and an image background, which gave me full control over the visual appearance of the "items". I also found it very useful to manipulate the underlying CALayer of many of my other UIViews. It is often easier than drawing things from scratch using Core Graphics programming.
Another thing that was useful were the UIGestureRecognizer:s. I found them useful for both handling "real" gestures like swiping, longpress etc, but also for handling normal "tap" for UIView classes that aren't subclasses of UIControl. Two examples are UIImage, UILabel and UIView itself. That way I could handle taps for these simple classes. I could for example use a normal UIView, modify it's CALayer to change the look of it completely and still handle taps. Using this technique, I didn't have to subclass any views at all in my app.
The animations were pretty easy too, even though I had to use a non-public method to use "suck" animation, so my app will never pass App Store moderation. It was just a prototype anyway so I don't care.
When this app will be for real, I will probably implement it in HTML5/JavaScript wrapped by Phonegap. The reason for this is mainly reuse of existing mobile web services and also for code reuse across platforms. It will probably also be easier to hook into the existing security solution when using a webapp.
Cocos2d is great if you need to move elements around really fast as it is a layer on top of OpenGLES. I think from what you have said the UIKit will be fine, you get nice animation support, you can do some nice things with UIScrollViews to handle moving elements around etc.
If you need more detailed graphics support and lots of moving elements, particle effects etc then by all means go for Cocos2D but be aware that in Cocos2d the application works more on a scheduled update method, i.e. you get notified every 1/60th of a second to move stuff draw stuff etc, whereas with normal UIKit approach it is more event drive, i.e. I click a button and show a view etc.
I would like to know how to create a custom iPhone control from scratch, or using an existing library or framework.
I have seen the three20 library, aswell as tapku and touch customs which are nice for specialised iOS controls such as table view etc but I'm talking about making totally custom, interactive controls here.
Lets say I wanted to make a dial control similar to the one from this app: http://store.apple.com/us/product/H2654LL/A.
Where would I start?
Would I subclass UIView and customize it?
Would I use quartz 2d?
Would I use OpenGL ES to draw something like this to the screen?
Can I still use IB to design/layout my custom view?
I'm just a bit confused which way to go here.
Yes - this question has been asked and answered a few times before, but I am yet to find a satisfactory answer which addresses the above points.
What to subclass
Instead of UIView you would probably want to subclass UIControl. This class has functionality for the Target/Action pattern build in which you can use to respond to actions generated by your custom control. Most elements on UIKit like buttons and sliders inherit from UIControl for this specific reason.
Visualizing your subclass
Drawing really depends on what you want to achieve and what parts you want to animate. You can use images, draw using quartz or OpenGL depending on what you need or what you prefer. Just use the technique to achieve the desired effect in the most simplistic way. Multiple images can be used to handle different states (pressed, etc) or be used for a sprite animation. CALayers are nice to easily rotate or move.
No matter what technology you use, you would probably use incoming touch events to control the animation. In case of a dial control you would control the amount of rotation based on y coordinate movement for example.
To illustrate: I for example have used images if my control only needed to change when pressed for example: just swap the images. I also like to use CALayer a lot which gives you easy ways to generate borders, masks, gradients and a corner radius, all easily animated too.
Using in Interface Builder
With Cocoa on the desktop it was possible to build custom IB palettes for custom controls. iOS never had this functionality and I don't thing the IB plugins are available for Xcode 4.
So the only way to handle custom subclasses currently is by using a UIView in IB and setting the 'Custom class' field in the Identity Inspector to the name of your custom class. This way you have a view you can layout and size. In Interface Builder it's just a rectangle, when running your app the XIB will actually deserialize that view to your custom class.
When using a UIControl you get the target/action mechanisms for free. So you can wire up your touch events to any object in IB just like with any other standard UIKit control.
One thing to note: if you have custom - initWith....: selectors, those will not be called. Your class is deserialized from the XIB so you should use - initWithCoder:(NSCoder *)aDecoder; as initialization.
Also there are quite few custom controls on http://www.cocoacontrols.com/platforms/ios/controls. They are open source hence you can download source and play with them.
I'm pretty new to iphone development, so this is more of a high-level question. The simplest description of what I am looking to do is create a zoomable/panable field on which I can place a bunch of circle objects. The number of these circles is likely to be in the hundreds, and ideally when the user zooms in close enough, more information can be displayed. From stuff I've read, it seems like UIScrollView provides the simplest way of making a zoomable/panable view but I'm not sure it's the best way to handle a view that includes a hundred graphic objects. I'm trying to figure out if I should progress further down that path or look into things like CALayers, Core Graphics, etc. Any guidance or advice would be greatly appreciated. Thanks in advance,
Roman
I suggest you to use UIScrollView, because it will save a lot of time for handling proper zooming/scrolling. So the workflow is next:
1. Zoom you scroll view
2. In delegate's callback scrollViewDidEndZooming:withView:atScale: you can obtain the scale and determine the level of detail that you need.
3. redraw the visible region (using Core Graphics) with appropriate level of detail (number of circles etc.)
So you should use the mix of Core Graphics and UIKit.
I'm pretty new to the iPhone platform, so I'm wondering what the best way to switch between OpenGL rendering and a UIView might be?
Any comments much appreciated!
There's no need to switch modes at all. OpenGL ES rendering on the iPhone is done in a CAEAGLLayer Core Animation layer. This can be used as the base layer for a UIView, which means that you can combine all the UIView layout and touch handling with your 3-D rendering. This UIView can be fullscreen or placed anywhere on the display. UIViews also can be made subviews of your 3-D view, therefore they can appear above your rendering.
The OpenGL ES Application Xcode template gives you an OpenGL layer within a UIView instance and is a good place to start. For a more complex example, I can direct you to the source code for Molecules, my 3-D molecular viewer. In that application, I use a lot of the view functionality for touch detection and place an info button in the lower right as a subview. I even replace that view with another to produce a flip animation when going to the application's settings.