objective-c - c字符串转换到NSString

Question

我还在继续svn客户端的项目。我在objective-c对象体外，有个静态的c语言的回调方法。其中，我将char*转化成了NSString，调试时一切正常。但运行到后面的时候，字符串变量会丢掉，并且只要一取出这个属性，就报错。

char* 转换到NSString的代码：

static svn_error_t *
my_list_repo_func (void *baton,
                   const char *path,
                   const svn_dirent_t *dirent,
                   const svn_lock_t *lock,
                   const char *abs_path,
                   apr_pool_t *pool)
{
    printf ("%s\n",path);

    SrcEntry *srcEntry = [[SrcEntry alloc]init];
    // 注：后面取这个name属性时会报错
    srcEntry.name = [NSString stringWithUTF8String:path];
    srcEntry.path = [NSString stringWithUTF8String:abs_path];
    srcEntry.lastAuthor = [NSString stringWithUTF8String:dirent -> last_author];
    srcEntry.time = [NSNumber numberWithLong:dirent -> time];

    [srcEntries addObject:srcEntry];
    return SVN_NO_ERROR;
}

后面调用报错的地方(此处为一个tableview刷新时候的方法)：

- (id) tableView: (NSTableView *)table
objectValueForTableColumn: (NSTableColumn *)column
             row: (NSInteger)row {

    SrcEntry *srcEntry = [self.srcEntries objectAtIndex:row];
    return srcEntry.name;
}

最奇怪的是，我在刚开始转换完，调试看到的值和类型，和后面报错前看到的完全不一样。下面是两张调试变量时候的截图：

这张是报错前，调试变量截图：

注：就是在读取第二个元素的name属性的时候出错。这中间我并没有对数组里面的元素做任何改动，只是把数组拷贝到了另外一个地方。为什么类型和值都会发生变化呢？

追加：并且，从截图中可以看出属性path的值都丢掉了。变成了一串内存地址。难道我是需要用*符号，再取出实际的值吗？

追加2：第二张截图中，显示为（NSString *) xxxxx像是内存地址的name的属性。我试验了，调用任何方法都报错，并且像是死循环一样，断点一直反复进入那个地方出不来。请问有没有什么办法，绕过这个错？

Answer 1

What are the parameters of the @property (parameter 1, parameter 2) attribute of your srcEntry.name? Have you enabled ARC?

You said: I didn’t make any changes to the elements in the array, I just copied the array to another place.

---

e.g. The following is a scenario simulation
If you declare two properties like this:

@property (nonatomic, strong) NSString *string1;   

@property (nonatomic, weak) NSString *string2; 

and define

@synthesize string1;   

@synthesize string2;  

What is the output below?

self.string1 = @"String 1";   

self.string2 = self.string1;   

self.string1 = nil;  

NSLog(@"String 2 = %@", self.string2);  

The result is: String 2 = null

---

Since self.string1 and self.string2 point to the same address, and string2 does not retain the memory address, and self.string1=nil releases the memory, string1 is nil. For pointers declared as weak, once the address pointed to by the pointer is released, these pointers will be assigned a value of nil.

I think your name attribute is either weak or assign. It’s best to change it to copy