Question

一直在玩弄没有太多运气的乐器，以找出如何解决这种内存泄漏问题。

首先是代码：

-(NSString *) randomizeHint:(NSString *) wordToShuffle{

    NSMutableString * outputstring = [NSMutableString stringWithCapacity:[wordToShuffle length]];
    NSMutableSet * usedNumberSet = [NSMutableSet setWithCapacity:[wordToShuffle length]];

    for (int i=0; i<[wordToShuffle length]; i++) {
        int randomnum = arc4random()%[wordToShuffle length];

        while ([usedNumberSet containsObject:[NSNumber numberWithInt:randomnum]]==YES) {
            randomnum = arc4random()%[wordToShuffle length];
        }

        [usedNumberSet addObject:[NSNumber numberWithInt:randomnum]];
        [outputstring appendFormat:@"%c",[wordToShuffle characterAtIndex:randomnum]];
    }

    CCLOG(@"outputstring is:%@",outputstring);
    return outputstring;

 }

仪器给了我以下内容：

Leaked Object = NSCFString, Responsible Library = Foundation, Responsible Frame = -[NSPlaceholderMutableString initWithCapacity:]

有什么想法吗？

提前致谢。

Answer 1

你真的不需要使用可变字符串...特别是因为你的返回类型是NSString。只需使用stringByAppendingFormat：

-(NSString *) randomizeHint:(NSString *) wordToShuffle{

    NSString * outputstring = @"";

    NSMutableSet * usedNumberSet = [NSMutableSet setWithCapacity:[wordToShuffle length]];

    for (int i=0; i<[wordToShuffle length]; i++) {
        int randomnum = arc4random()%[wordToShuffle length];

        while ([usedNumberSet containsObject:[NSNumber numberWithInt:randomnum]]==YES) {
            randomnum = arc4random()%[wordToShuffle length];
        }

        [usedNumberSet addObject:[NSNumber numberWithInt:randomnum]];

        // just set outputstring like so... no need to worry about a leaky mutable string then
        outputstring = [outputstring stringByAppendingFormat:@"%c",
                    [wordToShuffle characterAtIndex:randomnum]];
    }


    return outputstring;

}

Answer 2

查看返回字符串的使用位置。可能你保留它并释放保留字符串的对象而不首先释放保留的字符串。仪器仍将指向此部分代码作为“泄露”对象。最困难的部分是找到'泄漏者'。是的，你可以泄漏一个字符串，我只是为它写了食谱。

需要帮助修复内存泄漏 - NSMutableString

2 个答案: