My rewrite of Dungeonators is crawling along at a glacial pace. Mostly because I can only work a couple of hours a week on the project. But the iOS 5 way to manage memory with ARC (automated reference counting) is making the process far less painful than it was the first time I wrote my game. ARC uses annotations and some new key words to manage memory on your behalf. It works very well if you’re doing simple client-side game development and don’t have to worry about backward compatibility with iOS 4.
Here is an example of how ARC changes your life for the better…
In the old days you would declare out your ivars, declare your properties, then synthesize and map them together, and release them in a dealloc method. This little design pattern required 4 repetitive lines of code for every ivar (instance variable) and engendered flamewars about coding style and where underscore should go (if you thought it was necessary to distinguish an ivar name from a property name).
Pre-ARC Entity.h
#import "cocos2d.h"
@interface Entity : CCSprite {
BOOL isActive_;
NSString * name_;
}
@property (nonatomic) BOOL isActive;
@property (nonatomic, copy) NSString * name;
@end
Pre-ARC Entity.m
#import "Entity.h"
@implementation Entity
@synthesize isActive = isActive_;
@synthesize name = name_;
- (id) init {
self = [super init];
if (self) {
isActive_ = YES;
name_ = @"Fang";
}
return self;
}
- (void) dealloc {
[name_ release];
name_ = nil;
[super dealloc];
}
In this new modern era of automated reference counting I just declare properties, I don’t worry about accessing the ivars directly, and I don’t write my own dealloc. It’s a lot less code in a complex game where characters and objects have dozens of properties.
Post-ARC Entity.h
#import "cocos2d.h" @interface Entity : CCSprite @property (nonatomic) BOOL isActive; @property (nonatomic, strong) NSString * name; @end
Post-ARC Entity.m
#import "Entity.h"
@implementation Entity
@synthesize isActive;
@synthesize name;
- (id) init {
self = [super init];
if (self) {
isActive = YES;
name = @"Fang";
}
return self;
}
To get Cocos2d-iPhone to work with ARC was really easy: I just replace the NSAutoreleasePool object in main.m with the new ARC friendly @autoreleasepool annotation. (I might not have had to do this but it’s supposedly more efficient.)
int main(int argc, char *argv[]) {
// NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];
// int retVal = UIApplicationMain(argc, argv, nil, @"AppDelegate");
// [pool release];
// return retVal;
int retVal;
@autoreleasepool {
retVal = UIApplicationMain(argc, argv, nil, @"AppDelegate");
}
return retVal;
}
The downside, as I stated above, is that your app will only run on iPhones, iPads, and iPods running iOS 5 and you need to use Cocos2d-iPhone 2.0. But I think that’s a fair tradeoff. Backward compatibility is a killer of the artistic soul and should be avoided where possible. To Err is human, but to upgrade is divine 🙂
Check out Ray Wenderlich’s excellent ARC tutorial for all the gritty details!