Re-assignment of variable doesn't work

Question

I have a puzzling problem -- it seems like it should be so easy to do but somehow it is not working. I have an object called Player. The Manager class has four instances of Player:

@interface Manager
{
    Player *p1, *p2, *mCurrentPlayer, *mCurrentOpponent;  
}
// @property...

The Manager object has initPlayers and swapPlayers methods.

-(void) initPlayers {  // this works fine
    self.p1 = [[Player alloc] init];
    self.p2 = [[Player alloc] init];
    self.mCurrentPlayer = self.p1;
    self.mCurrentOpponent = self.p2;
}

-(void) swapPlayers {  // this swapping of pointer doesn't work
    self.mCurrentPlayer = self.p2;
    self.mCurrentOpponent = self.p1;

    // When I look at the pointer in debugger, self.mCurrentPlayer is still self.p1.  :-(

    // I even tried first setting them to nil, 
    // or first releasing them (with an extra retain on assignment) to no avail
}

What am I missing? Thanks in advance!

Answer 1

Without knowing how your accessors are set up, it will be difficult to troubleshoot the code as-is. That being said, here is how your accessors and code should be set up:

Manager.h

@interface Manager 
{
    Player *p1, *p2, *mCurrentPlayer, *mCurrentOpponent;
}
@property (nonatomic, retain) Player *p1;
@property (nonatomic, retain) Player *p2;
@property (nonatomic, assign) Player *mCurrentPlayer;
@property (nonatomic, assign) Player *mCurrentOpponent;
@end

Manager.m

-(void) initPlayers {
    self.p1 = [[[Player alloc] init] autorelease];
    self.p2 = [[[Player alloc] init] autorelease];
    self.mCurrentPlayer = self.p1;
    self.mCurrentOpponent = self.p2;
}

-(void) swapPlayers {
    Player * temp = self.mCurrentPlayer;
    self.mCurrentPlayer = self.mCurrentOpponent;
    self.mCurrentOpponent = temp;
}

Answer 2

It turns out the problem was somewhere unrelated in the code and I misread the symptoms of the problem! But just for the sake of discussion, why is it necessary to have @property on multiple lines, and to use a temp variable to swap the players (as per e.James answer)?