Problem initializing an object with init in Objective-C - iphone

Question

I have an object that i intalize it's propertis with call to an init function, it works fine,
when i tried to add another object and intalize it the first object didn't get the properites, how do i initalize it to more then one object with diffrent or the same properties?
- (void)viewDidLoad {
pic1 = [[peopleAccel alloc] init];
}
Class peopleAccel:
- (id) init
{
self = [super init];
if (self != nil) {
position = CGPointMake(100.0, 100.0);
velocity = CGPointMake(4.0, 4.0);
radius = 40.0;
bounce = -0.1f;
gravity = 0.5f;
dragging = NO;
[[UIAccelerometer sharedAccelerometer] setDelegate:self];
acceleratedGravity = CGPointMake(0.0, gravity);
}
return self;
}

Answer 1

I see a problem with setting the delegate of sharedAccelerometer. Only one object can be a delegate of another object at a time. So you should create only one peopleAccel object.
EDIT:
If you need to send accelerometer events to more than one object, you can create a specific delegate object in charge of receiving accelerometer events and broadcasting them to your several peopleAccel objects via notifications. See this question for some hints: NSNotificationCenter vs delegation?

Answer 2

Create a proxy so multiple objects can receive accelerometer events.
Whether you should do this or use NSNotificationCenter is debatable and there are two camps, but personally I would use this approach. NSNotificationCenter has to check string names to recognise event type; this kind of approach could be ever so slightly faster especially with a bit more optimisation. A bit more typing but I would say also easier for someone else to follow.
Something like this...
/* PLUMBING */
/* in headers */
#protocol MyAccelSubDelegate
-(void)accelerometer:(UIAccelerometer*)accelerometer
didAccelerate:(UIAcceleration*)acceleration;
#end
#interface MyAccelSubDelegateProxy : NSObject <UIAccelerometerDelegate> {
NSMutableArray subDelegates;
}
-(id)init;
-dealloc;
-(void)addSubDelegate:(id<MyAccelSubDelegate>)subDelegate;
-(void)removeSubDelegate:(id<MyAccelSubDelegate>)subDelegate;
- (void)accelerometer:(UIAccelerometer *)accelerometer didAccelerate:
(UIAcceleration *)acceleration;
#end
/* in .m file */
#implementation MyAccelSubDelegateProxy
-(id)init { self = [super init];
if (self!=nil) subDelegates = [[NSMutableArray alloc] init]; return self; }
-dealloc { [subDelegates release]; }
-(void)addSubDelegate:(id<MyAccelSubDelegate>)subDelegate {
[subDelegates insertObject:subDelegate atIndex:subDelegates.count]; }
-(void)removeSubDelegate:(id<MyAccelSubDelegate>)subDelegate {
for (int c=0; c < subDelegates.count; c++) {
id<MyAccelSubDelegate> item = [subDelegates objectAtIndex:c];
if (item==subDelegate) { [subDelegates removeObjectAtIndex:c];
c--; continue; }
}
}
- (void)accelerometer:(UIAccelerometer *)accelerometer didAccelerate:
(UIAcceleration *)acceleration {
for (int c=0; c < subDelegates.count; c++)
[((id<MyAccelSubDelegate>)[subDelegates objectAtIndex:c])
accelerometer:accelerometer didAccelerate:acceleration];
}
#end
/* SOMEWHERE IN MAIN APPLICATION FLOW STARTUP */
accelProxy = [[MyAccelSubDelegateProxy alloc] init];
[UIAccelerometer sharedAcclerometer].delegate = accelProxy;
[UIAccelerometer sharedAcclerometer].updateInterval = 0.100; // for example
/* TO ADD A SUBDELEGATE */
[accelProxy addSubDelegate:obj];
/* TO REMOVE A SUBDELEGATE */
[accelProxy removeSubDelegate:obj];
/* SOMEWHERE IN MAIN APPLICATION SHUTDOWN */
[UIAccelerometer sharedAcclerometer].delegate = nil;
[accelProxy release];