Code Day Notes

In Objective-C there are compiler directives for instance variables: @private, @protected and @public but you can't use it for your methods. If you wan't to hide some methods you can use it like this : 

File Test.h :  

@interface Test : Object 

+(void) classMethod {} 

-(void) instanceMethod{} 

@end 

File Test.m 

#import "Test.h" 

@interface Test (hidden) 

+(void) hiddenClassMethod; 

-(void) hiddenInstanceMethod;  

@end  

@implementation Test (hidden) 

+(void) hiddenClassMethod {}  

-(void) hiddenInstanceMethod {} 

@end  

@implementation Test  

+(void) classMethod {} 

-(void) instanceMethod{} 

As a lot of iphone libraries (Cocos2D, Chipmunk...) use structures for basic elements, you sometimes need to use dynamic arrays. If you do not want to wrap C++ code in your Objective-C sources (using vectors or other STL container) you can use a trick that helps storing data structure into basic Objective-C arrays. Example with vertex of a circle in Cocos2D :

NSMutableSet *circleVertex = [[NSMutableSet alloc] init];

for(float theta = 0; theta < 2*M_PI; theta += M_PI/8) {

        float x = circle.center.x + circle.radius * cos(theta);

        float y = circle.center.y + circle.radius * sin(theta);

        CGPoint p = ccp(x,y);

        NSValue *point = [NSValue value:&p withObjCType:@encode(CGPoint)];

        [circleVertex addObject:point];

}

For getting the value :

for(NSValue *val in circleVertex) {

        CGPoint p;

        [val getValue:&p];