There are many Cocos2D + Storyboard tutorials, it’s about time to do another one that’s done right. Also, this one’s backwards: we’ll start with a Cocos2D template and then add Storyboards to it. The tutorial will work for existing Cocos2D projects to which you wish to add Storyboards, too!
I’ll show you how to add Storyboards to a Cocos2D v2.1 project, with ARC enabled of course. This approach will take a little more work, but the solution will be complete and you gain a fair understanding of how things work together. Plus two custom but reusable View and Navigation controller classes, and I’ll show you what changes you need to make to the AppDelegate.
The resulting project will work with iOS 5 and iOS 6 and autorotation. The navigation and cocos view controllers are separated, and you will be able to subclass them for code customizations as is customary in Cocoa. Cool? Cool, cool, cool!
As usual you can grab the example project (Cocos2D + Box2D + Storyboards with ARC enabled) from github. I’ll also be adding a Storyboards template project to KoboldTouch in the next update, and document what’s special about the KoboldTouch solution.
Oh, only one thing … this tutorial is part of Essential Cocos2D. Head on over and enjoy!
KoboldTouch v6.2 marks the third major milestone for KoboldTouch. It also marks the longest development cycle between two updates: exactly 30 days.
That’s 30 days packed with new features, improvements and bugfixes, there’s a new development blog for the work-in-progress “Angry Trains” starterkit and slowly but surely the documentation is coming together.
So let’s check out the exciting new features in KoboldTouch v6.2:
Objective-C Box2D Physics wrapper
The Objective-C wrapper for Box2D (aka “Boxjective2D”) is now in a state that I feel very comfortable with. And proud. It’s the only Box2D Objective-C wrapper that’s both fairly complete and supported and will be continuously improved. It’s also stable, super-slick and easy to use, highly efficient without compromising integrity (ie no @private vars) and you can always access the underlying Box2D objects.
The following Box2D components are wrapped in Objective-C classes, which is about 80% of the public API of Box2D (and I won’t stop there): Continue reading »
In order to write Tiled’s TMX file format I needed to do exactly this: figure out how to compress data, encode it as a string, and write it to XML.
I wrote down what I learned from using zlib, base64 and xswi – XML Stream writer for iOS (a single Objective-C class) while writing KoboldTouch‘s TMX writer.
I split it into two articles in the Essential Cocos2D section of the www.KoboldTouch.com homepage:
- How to compress and encode data with zlib and base64
- How to write XML on iOS with xswi (XML Stream Writer)
I was positively surprised how relatively painless zlib and base64 encoding worked (I expected the worst!) and how simple and effective xswi is for writing XML compared to any other XML library.
I’ll probably continue to add those articles to Essential Cocos2D rather than posting them on this blog. Confluence is just so much more convenient for writing technical documentation than WordPress.
Final word: Enjoy! 
I already blogged about scaling node positions with display resolution. This feature is now built into KoboldTouch. Time for a demonstration before I get back to work on an improved Tilemap renderer:
The cool thing about KoboldTouch autoscaling is that it works transparently. Your nodes will be positioned relative to the design resolution, for example 480×320. The nodes will continue to use the same position on any device! So you just develop these nodes’ positions and their movement as if they were always on a 480×320 device. It’s that simple.
It also works for movement of any kind, be it CCMove* actions or manually updating the position property every frame. Moving nodes continue to move seemlessly even when you rotate the device. Continue reading »
Here’s a quick tip on how to design your scenes so that they scale up to higher resolution displays. For example when your app runs on a widescreen iPhone / iPod touch or on an iPad. This article is not about Retina displays, which use the same coordinate system and merely display higher resolution images.
Design for the lowest supported resolution
First, design your game to the lowest device/window resolution that your app supports. In most cases this will be the 480×320 points used by the majority of iPhones.
Contrary to images, you always want to scale your designed screen layouts up and never down. This is because upscaled screens will always fit on the device’s display, with more or less additional spacing between the nodes. Downscaling however might cause screen elements to overlap, which is hard to fix if you don’t see the overlap in the resolution you design for.
It’s also easier to make manual changes to upscaled screen layouts than it is for downscaled screen layouts.
Calculate the scaling factor
By dividing the current device/window size with the resolution you designed for, you get the scaling factor by which you have to multiply positions. This is a simple wrapper you can use:
|
1 2 3 4 5 6 7 8 9 |
static CGSize designSize = {480, 320}; -(CGPoint) scalePoint:(CGPoint)point { CGSize winSize = [CCDirector sharedDirector].winSize; CGSize scaleFactor = CGSizeMake(winSize.width / designSize.width, winSize.height / designSize.height); return CGPointMake(point.x * scaleFactor.width, point.y * scaleFactor.height); } |
To make a node’s position resolution independent, use the position you would use for a 480×320 screen and scale it up:
|
1 2 |
// centers the sprite, regardless of window size sprite.position = [self scalePoint:CGPointMake(240, 160)]; |
This even works for autorotation. If you use NSNotificationCenter to receive orientation change events, you can use the scalePoint method with the current position to generate the node’s position after the rotation happened. You can try by simply changing the designSize to {320, 480} and setting the app’s default orientation to Portrait.
Caveats
Of course it’s entirely up to you what makes sense, which nodes can be scaled and which should not. For example squeezing a landscape app in portrait mode is possible, but it simply won’t make for a good user experience. However scaling HUD elements that should be aligned with one side of the screen so that they automatically stick to the side of the screen (ie widescreen iPhones, iPad) would be a huge timesaver.
If you update your node’s positions manually in order to move them, then you may have to also scale the amount by which the node moves. It’s easy to do by multiplying the movement vector with the same scale factor.
This won’t work well for actions, which may run faster (or sometimes even slower) depending on window size and aspect ratio. But it’ll work with actions nonetheless if you also apply the scale factor to the target position.
Another issue to watch out for is to accidentally scale up a position, and then scale it up again. This can happen if you’re not careful when updating more complex algorithms or dependencies where more than one method updates the node’s position. The best way to avoid that is to ignore scaling until just before the screen is drawn. You could override the draw or visit method (don’t forget to call super) and scale the position:
|
1 |
self.position = [self scalePoint:self.position]; |
After drawing is complete you could then reset the position back to its original by dividing by the scale factor. I’ll leave it up to you to add a convenience method for that. That would make the position scaling completely transparent to your app and you could simply consider all screens to be in the designed for resolution.
KoboldTouch
I will be adding a KTAutoscaleController to KoboldTouch soon to make this easier for KT users. This will be a really nice feature to have, and really easy to use:
|
1 2 3 4 5 6 7 |
KTAutoscaleController* autoscaleController = [KTAutoscaleController controller]; autoscaleController.designResolution = CGSizeMake(480.0f, 320.0f); [self addSubController:autoscaleController]; // autoscale this sprite's position depending on window size [autoscaleController autoscaleNode:sprite scaledProperties:KTAutoscalePropertyPosition]; |
Until next year, have an enjoyable year’s end!
There are two classes of scrolling, "fake" and "real".
Altogether there are four ways to create a scrolling view in Cocos2D: with CCCamera, with CCFollow, manually moving a layer and "faking it".
I’ll discuss each approach and show their advantages and disadvantages as well as point out for which types of games they work best.
The example projects for this article can be downloaded from github.
Fake Scrolling – Creating the Illusion of Movement
Ideal for "endless scrolling" games. Typical genres include jumping or running games like Doodle Jump and Canabalt, as well as shoot’em ups.
These games mainly scroll along one axis, often scrolling only in one direction. The other axis has a limited range or is not scrolled at all. The fake scrolling approach prevents the coordinates of game objects to "explode" to similarly infinite coordinate points. This could introduce rounding errors in floating point values which may accumulate over time, causing inaccuracies at later stages of the game.
To create the illusion of scrolling, at least two background image sprites are needed. Four are needed if you also want to scroll a little along the minor scrolling axis. The background images must be repeating seamlessly, and each must be at least the size of the screen. The trick is to use the two or four images and move them in the opposite direction of where the player is supposedly heading. Continue reading »
I’m currently completing one last contract project. One of the last things I had to deal with was to optimize the game’s memory usage.
In today’s iDevBlogADay article I’ll explain how I was able to cut down memory usage by about 25-30 MB (down to 90-95 MB, ie fixing memory warning related crashes) as well as reducing the size of the app bundle from around 25 MB to below 20 MB (which would have been more awesome if Apple hadn’t already increased the over-the-air download limit from 20 MB to 50 MB some time ago).
I’ll also explain how to animate the loading screen while you’re loading resource files, and I’ll add some best practices and common wisdom too.
What’s using 90% of the memory?
Take a guess.
In almost all cases, it’s textures that consume most of the app’s memory. So textures is where you look to optimize first and foremost if you’re having memory warning troubles.
Avoid loading PNG/JPG Textures one after another
The problem with texture loading in cocos2d is that it happens in two steps: first, a UIImage is created from the image file. Then a CCTexture2D object is created from that UIImage. This means while a texture is being loaded, it will consume twice as much memory for a short time period.
The problem used to be so bad that if you loaded 4 textures one after another in the same method, at the end of the method each texture would still consume twice as much memory as it ought to, probably because of the way autorelease works.
I’m not sure if this is still the case, or whether this only applies to manual reference counting but not ARC. I made it a habit to load textures in sequence, waiting at least one frame before trying to load another. This will allow any texture loading overhead to be released from memory. Besides, as you’ll see later, if you want to load textures and other assets in the background this asset-load-sequencing is something you’ll do anyway.
Loading ...
