xcode目标c，EXC_BAD_ACCESS

Question

I have this property in my .h file:

@property (nonatomic, readwrite) NSInteger gameMode;

And I have this setter in the corresponding .m file:

- (void)setGameMode:(NSInteger)mode {
    self.gameMode = mode;
    NSLog(@"game mode %d", self.gameMode);
}

In my view controller, I have this function to call the setter when I touch a button:

- (IBAction)touchCardButton:(UIButton *)sender {
    if ([self.game disableModeChooseAtFirstTouch]) {
        [self.game setGameMode:self.modeSegmentedControl.selectedSegmentIndex];
}

But when I click the button in simulator, it will stop here:

self.gameMode = mode;

And says:

Thread 1: EXC_BAD_ACCESS

Update: If I add a NSLog before it, like this:

- (void)setGameMode:(NSInteger)mode {
    NSLog(@"game mode %d", self.gameMode);
    self.gameMode = mode;
    NSLog(@"game mode %d", self.gameMode);
}

It will keep printing game mode: 0

Can anybody tell me why? Thanks!

Answer 1

Yes, I can tell you why. You are invoking the setter in the setter, causing infinite recursion, stack overflow, and a crash.

Your setGameMode method should read:

- (void)setGameMode:(NSInteger)mode 
{
    _gameMode = mode;  //Don't use the setter in the implementation of the setter.
    NSLog(@"game mode %d", self.gameMode);
}