Question

我有一个令人费解的问题 - 似乎应该这么容易做但不知何故它不起作用。我有一个名为Player的对象。 Manager类有四个Player实例：

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

Manager对象具有initPlayers和swapPlayers方法。

-(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
}

我错过了什么？提前谢谢！

Answer 1

如果不知道如何设置访问者，就很难对代码进行故障排除。话虽如此，这里是你的访问者和代码应该的设置方式：

<强> 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

<强> 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

事实证明问题在代码中无处不在，我误解了问题的症状！但仅仅为了讨论，为什么有必要在多行上使用@property，并使用temp变量来交换玩家（根据e.James的回答）？

重新分配变量不起作用

2 个答案: