Xcode 4.4中架构x86_64的未定义符号

Question

我最近在Mountain Lion上运行了Xcode 4.4的新项目.我有一个名为的类TSTopChartManager,它位于我项目的MainMenu笔尖中.我还有一个名为的数据容器PodcastShow,它基本上有一堆属性和一个从互联网上获取图像的方法.这TSTopChartManger看起来像......

.h文件......

#import <Foundation/Foundation.h>
#import "PodcastShow.h"

@interface TSTopChartManager : NSObject

@property NSMutableArray *topPodcasts;
@end

.m文件:

#import "TSTopChartManager.h"

@implementation TSTopChartManager
-(id) init
{
    if (self)
    {
        /*PodcastShow *myShow = [[PodcastShow alloc] init];
        myShow.title = @"This is a show";*/
    }
    return self;
}
@end

现在,它完美运行.但是当我在init方法中删除块注释时就像这样......

if (self)
    {
        PodcastShow *myShow = [[PodcastShow alloc] init];
        myShow.title = @"This is a show";
    }

我收到以下错误..

Undefined symbols for architecture x86_64:
  "_OBJC_CLASS_$_PodcastShow", referenced from:
      objc-class-ref in TSTopChartManager.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)

我不知道为什么会这样.我以前没见过这样的错误.我该怎么办呢？有任何想法吗？谢谢!

对于好奇: PodcastShow在我的应用程序中被视为数据容器.它有一些属性和两种方法.这是PodcastShow看起来像:

.H:

#import <Foundation/Foundation.h>

@interface PodcastShow : NSObject
{
    NSString *title;
    NSString *network;
    NSString *imageURL;
    NSImage *image;
    NSString *link;
    NSString *description;
}
-(void) fetch;
@property (strong, readwrite) NSString *title;
@property (strong, readwrite) NSString *network;
@property (strong, readwrite) NSString* imageURL;
@property (strong) NSImage *image;
@property (strong, readwrite) NSString *identification;
@property (strong, readwrite) NSString *link;
@property (strong, readwrite) NSString *description;
@end

L:

#import "PodcastShow.h"

@implementation PodcastShow
-(id) init
{
    if (self)
    {
        NSLog(@"initilized");
    }
    return self;
}

-(void) fetch
{
    [NSThread detachNewThreadSelector:@selector(getImageFromInternet) toTarget:self withObject:nil];
}

-(void) getImageFromInternet
{
    self.image = [[NSImage alloc] initWithContentsOfURL:[NSURL URLWithString:self.imageURL]];
}
@end

Answer 1

可能PodcastShow.m不是构建阶段的一部分.在项目导航器中单击它,然后在文件信息中查看屏幕右侧.确保勾选了您的应用目标.