Question

我真的非常绝望。我正在尝试制作一个框架，您可以搜索和播放YouTube视频。但在测试时，我遇到了一个大问题。

在搜索操作中，我将YTVideos（NSObject的子类）添加到NSMutableArray。当我在main（）中循环它时，我得到的是nil-objects：

方式

- (NSArray *)videosInRange:(NSRange)range {
 if(range.length > 50) {
  [NSException raise:@"Range lenth > 50"
     format:@"The range of -videosInRange: can't be bigger than 50"];
  return nil;
 }

 if((range.location + range.length) > 999) {
  [NSException raise:@"Range to big" 
     format:@"The given range was to big (%d, %d)", range.location, range.length];
  return nil;
 }

 NSString *searchURLString = [[self feedURL] absoluteString];
 searchURLString = [searchURLString stringBySettingURLAttribute:@"start-index" value:[NSString stringWithFormat:@"%d",range.location + 1]];
 searchURLString = [searchURLString stringBySettingURLAttribute:@"max-results" value:[NSString stringWithFormat:@"%d",range.length]];

 NSLog(@"%@",searchURLString);
 NSURL *url = [NSURL URLWithString:searchURLString];
 NSXMLDocument *xmlDoc = [[NSXMLDocument alloc] initWithContentsOfURL:url 
                 options:0
                   error:NULL];
 if(!xmlDoc)
  return nil;

 NSArray *videoElements = [[xmlDoc rootElement] elementsForName:@"entry"];
 NSMutableArray *videos = [[NSMutableArray alloc] initWithCapacity:[videoElements count]];
 register int i;
 for(i = 0; i < [videoElements count]; i++) {
  NSAutoreleasePool *addPool = [[NSAutoreleasePool alloc] init];

  YTVideo *vid = [[YTVideo alloc] initWithXMLElement:[videoElements objectAtIndex:i]];
  [videos addObject:vid];
  [vid release];

  [addPool drain];
 }

 NSArray *retValue = [NSArray arrayWithArray:videos];
 [videos release];
 return retValue;
}

主要（）

int main(int argc, const char *argv[]) {
 NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];

 YTSearchFeed *feed = [[YTSearchFeed alloc] initWithSearch:@"Eminem"];
 long long results = [feed videoCount];
 NSLog(@"%lld videos for search", results);

 long long i = 0;
 while(results != 0) {
  int length = (results >= 50) ? (50) : (results);

  NSArray *videos = [feed videosInRange:NSMakeRange(i, length)];
  NSLog(@"L: %d", [videos count]);
  int z;
  for(z = 0; z < [videos count]; z++, i++) {
   YTVideo *vid = [videos objectAtIndex:z];
   NSString *title = [vid title];
   NSLog(@"%d: %@", i+1, title);
  }

  results -= length;
 }

 [pool drain];

 return NSApplicationMain(argc, argv);
}

我希望有人可以花时间看看这个，如果你需要更多信息，请问。

提前谢谢你， ief2

编辑：YTVideo

- (id)initWithXMLElement:(NSXMLElement *)element {
    self = [super init];
    if(self != nil) {
        _XMLElement = [element copy];
    }
    return self;
}

- (NSString *)title {
    if(!_title) {
        NSString *str = [[[self XMLElement] firstElementWithName:@"title"] stringValue];
        _title = [[str stringByDecodingHTMLEntities] retain];
    }

    return [[_title copy] autorelease];
}

只有在请求时才能获得标题（以及其他视频信息）。 -stringByDecodingHTMLEntities工作正常（NSString上的类别）。

Answer 1

我重写了代码并初始化了-init方法

中的所有实例变量

NSMutableArray和自定义NSObject的问题

1 个答案: