发送到实例的无效选择器 - objectForKey：
运行我的代码时出现错误。罪魁祸首是我从下面的 plist 中访问一个字符串：
NSString *sImageFile = [dictionary objectForKey:@"answerCorrect"];
NSLog(@"%@",sImageFile);
我的 cocos2d Init 中有这个，如下所示：
-(id) init
{
// always call "super" init
// Apple recommends to re-assign "self" with the "super" return value
if( (self=[super init])) {
NSUserDefaults *sud = [NSUserDefaults standardUserDefaults];
NSString *ctlLang = [sud valueForKey:@"ctlLang"];
NSNumber *questionState = [sud valueForKey:@"questionState"];
NSNumber *scoreState = [sud valueForKey:@"scoreState"];
gameArray = (NSMutableArray *)[sud valueForKey:@"gameArray"];
for (NSString *element in gameArray) {
NSLog(@"\nQL gameArray value=%d\n", [element intValue]);
}
NSString *path = [[NSBundle mainBundle] bundlePath];
NSString *finalPath = [path stringByAppendingPathComponent:ctlLang];
dictionary = [NSDictionary dictionaryWithContentsOfFile:finalPath];
NSString *sImageFile = [dictionary objectForKey:@"answerCorrect"];
NSLog(@"%@",sImageFile);
}
}
字符串的打印在场景的 init 部分工作正常。问题出现在我后面定义的一个方法中。由于某种原因，它没有返回此处显示的方法中的字符串：
-(void) checkAnswer: (id) sender {
CGSize size = [[CCDirector sharedDirector] winSize];
CCMenuItemSprite *sAnswer = (CCMenuItemSprite *)sender;
NSLog(@"Checking Answer Tag is ---> %d",sAnswer.tag);
NSString *sImageFile = [dictionary objectForKey:@"answerCorrect"];
NSLog(@"%@",sImageFile);
if ([question.answer integerValue] == sAnswer.tag) {
//...
}
}
我在这里缺少什么？程序在 NSLog 语句处爆炸。
I get an error when running my code. The culprit is me accessing a string from a plist below:
NSString *sImageFile = [dictionary objectForKey:@"answerCorrect"];
NSLog(@"%@",sImageFile);
I have this in my cocos2d Init shown here:
-(id) init
{
// always call "super" init
// Apple recommends to re-assign "self" with the "super" return value
if( (self=[super init])) {
NSUserDefaults *sud = [NSUserDefaults standardUserDefaults];
NSString *ctlLang = [sud valueForKey:@"ctlLang"];
NSNumber *questionState = [sud valueForKey:@"questionState"];
NSNumber *scoreState = [sud valueForKey:@"scoreState"];
gameArray = (NSMutableArray *)[sud valueForKey:@"gameArray"];
for (NSString *element in gameArray) {
NSLog(@"\nQL gameArray value=%d\n", [element intValue]);
}
NSString *path = [[NSBundle mainBundle] bundlePath];
NSString *finalPath = [path stringByAppendingPathComponent:ctlLang];
dictionary = [NSDictionary dictionaryWithContentsOfFile:finalPath];
NSString *sImageFile = [dictionary objectForKey:@"answerCorrect"];
NSLog(@"%@",sImageFile);
}
}
The printing of the string works fine in the init section of the scene. The problem occurs in a method I define later. For some reason it is not returning the string in the method shown here:
-(void) checkAnswer: (id) sender {
CGSize size = [[CCDirector sharedDirector] winSize];
CCMenuItemSprite *sAnswer = (CCMenuItemSprite *)sender;
NSLog(@"Checking Answer Tag is ---> %d",sAnswer.tag);
NSString *sImageFile = [dictionary objectForKey:@"answerCorrect"];
NSLog(@"%@",sImageFile);
if ([question.answer integerValue] == sAnswer.tag) {
//...
}
}
What am I missing here? the program bombs at the NSLog statement.
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评论（2）
您将
dictionaryWithContentsOfFile:返回的对象分配给dictionaryivar，但您并不通过向其发送retain消息来声明其所有权：dictionaryWithContentsOfFile:方法返回一个不属于您的对象。也许，在执行checkAnswer:时，对象已经被释放。您需要保留它：或者使用
alloc-initWithContentsOfFile:来代替，它返回一个您拥有的对象：gameplayivar 也是如此。您不拥有由valueForKey:返回的对象，并且您需要保留它。所以这一行：应该是：
You assign the object returned by
dictionaryWithContentsOfFile:to thedictionaryivar but you do not claim ownership of it by sending it aretainmessage to it:The method
dictionaryWithContentsOfFile:returns an object you do not own. Probably, by the timecheckAnswer:is executed the object has already been deallocated. You need to retain it:Or use
alloc-initWithContentsOfFile:instead, which returns an object you own:And the same goes for the
gameplayivar. You do not own the object returned byvalueForKey:and you need to retain it. So this line:should be:
我认为您不会保留在 init 方法中创建的自动释放字典。您设置了字典 ivar 但不保留它。当您稍后访问它时，它可能不再有效
I don't think you are retaining the autoreleased dictionary created in your init method. You set the dictionary ivar but don't retain it. When you access it later, it is likely not valid anymore