Question

我仍然堆叠着一个简单的objC代码，它从plist中检索一些数据。在我使用它们之后，我无法释放对象，因为它失败了......

- (void)retrieveFromPlist:(NSString*)Nazov
{
NSLog(@"Objekt: %@",Nazov);

NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);

NSString *documentsDirectory = [paths objectAtIndex:0];

NSString *path = [documentsDirectory stringByAppendingPathComponent:@"working.plist"];
////Zober vsetky ulozene

NSMutableDictionary *dict = [[NSMutableDictionary alloc] initWithContentsOfFile:path];
NSMutableDictionary *subDict = [[NSMutableDictionary alloc] init];
subDict = [dict objectForKey:Nazov];

NSString                    *hudbaR;
float                       hudbaL;
NSString                    *zvukR;
float                       zvukL;


hudbaL = [[subDict objectForKey:@"musicLevel"] floatValue];
hudbaR = [subDict objectForKey:@"musicRow"];
zvukL = [[subDict objectForKey:@"soundLevel"] floatValue];
zvukR = [subDict objectForKey:@"soundRow"];

NSLog(@"Musical level: %f, musical roww:%@ , zuk level: %f, zuk row: %@", hudbaL,hudbaR ,zvukL ,zvukR );



if (hudbaR) {
    [musicController setBackgroundSoundVolume:zvukL];
    [musicController setBackgroundMusicVolume:hudbaL];

    MusicsliderCtl.value = hudbaL;
    sliderCtl.value = zvukL;


    [musicController playMusicWithKey:hudbaR timesToRepeat:0];  
    [musicController playSoundWithKey:zvukR timesToRepeat:0];

}   

//[dict release];
//[subDict release];
}

Answer 1

NSMutableDictionary *subDict = [[NSMutableDictionary alloc] init];
subDict = [dict objectForKey:Nazov];

第二个语句会覆盖已分配的subDict。这会导致内存泄漏。然后，因为您不拥有[dict objectForKey:Nazov]，-release会导致解除分配错误。

你可以写

NSDictionary* subDict = [dict objectForKey:Nazov];

并且不要-release因为您不是所有者。（[dict release]仍然需要+alloc，因为你是{{1}}的人。）

如果您没有更改集合，请选择immutable（NSDictionary）over mutable（NSMutableDictionary）。

Answer 2

您正试图释放您的代码没有所有权的自动释放对象（subDict）：

NSMutableDictionary *subDict = [[NSMutableDictionary alloc] init];
subDict = [dict objectForKey:Nazov];

原始subDict变量被objectForKey:消息的返回值覆盖。导致首先泄漏原始对象，然后在自动释放池尝试释放新对象时崩溃。

要更正此问题，请删除代码中的以下行：

NSMutableDictionary *subDict = [[NSMutableDictionary alloc] init];
...
[subDict release];

从plist中检索后无法释放对象

2 个答案: