iphone - Objective-C NSString malloc 错误

Question

我有一个方法可以创建一个字符串，然后在其上附加其他字符串:

-(NSString*)returnDetails {
    NSString *details = [[NSString alloc] init];

    details = [details stringByAppendingString:url];
    details = [details stringByAppendingString:@" : "];
    details = [details stringByAppendingString:author];

    return [details autorelease]; 
}

我收到此错误:

iphoneapp_1(66508,0xacd9e2c0) malloc: *** error for object 0x6b9eb80: pointer being freed was not allocated

如果我把它改成

NSString *details = [NSString string];

并删除自动释放调用，然后它就可以工作了。我只是想了解为什么这有效而我原来的方法无效？

Answer 1

NSString 的方法 stringByAppendingString: 返回一个已经自动释放的对象。因此，从您的方法返回 [details autorelease] 将使该对象将被释放一次。只需返回详细信息即可。

那里还存在内存泄漏，因为您从未释放在方法顶部分配的字符串。试试这个代码:

-(NSString*)returnDetails {
    NSString *details = [NSString string];
    details = [details stringByAppendingString:url];
    details = [details stringByAppendingString:@" : "];
    details = [details stringByAppendingString:author];

    return details; 

}