Xcode 链接器错误：_OBJC_CLASS_$_CIImage
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Xcode Linker error: _OBJC_CLASS_$_CIImage
提问by Adam
When building my Xcode project I am receiving a Linker error that I cannot figure out how to resolve. If I build the following code the compile step completes just fine but I get an error from the Linker saying '"_OBJC_CLASS_$_CIImage", referenced from Objc-class-ref-to-CIImage in AppController.o' followed by a second error that looks identical except CIImage is replaced with CIFilter followed by a statement that says "Symbol(s) not found"
在构建我的 Xcode 项目时，我收到一个链接器错误，我不知道如何解决。如果我构建以下代码，编译步骤完成得很好，但我从链接器那里得到一个错误，说“_OBJC_CLASS_$_CIImage”，从 AppController.o 中的 Objc-class-ref-to-CIImage 引用'，然后是第二个错误看起来完全相同，除了 CIImage 被 CIFilter 替换，后跟一个说“找不到符号”的语句
CIFilter *transform = [CIFilter filterWithName:@"CIAffineTransform"];
[transform setValue:inputBitmap forKey:@"inputImage"];
NSAffineTransform *affineTransform = [NSAffineTransform transform];
[affineTransform rotateByDegrees:3];
[transform setValue:affineTransform forKey:@"inputTransform"];
CIImage * result = [transform valueForKey:@"outputImage"];
This code is in my AppController.m, and the Linker error showed up after I put the following statement up at the top:
这段代码在我的 AppController.m 中，在我将以下语句放在顶部后出现链接器错误：
#import "QuartzCore/CIFilter.h"
I put that import statement in because, without it I get a Compiler error on the first line of code that says "No +filterWithName method found" and I read somewhere that Cocoa automatically includes CIImage.h but not CIFilter.h. So ... with the #import the compiler error disappears but I get the linker error. :(
我把那个导入语句放进去是因为，如果没有它，我会在第一行代码中得到一个编译器错误，上面写着“没有找到 +filterWithName 方法”，我在某处读到 Cocoa 自动包含 CIImage.h 但不包含 CIFilter.h。所以......使用#import，编译器错误消失，但我收到链接器错误。:(
Any ideas what is causing the Linker error and how to get rid of it?
任何想法是什么导致链接器错误以及如何摆脱它？
FYI: I tried searching for duplicate files as described in another "xcode linker error" thread herein, but could not find any duplicate files in my project. I also went to the trouble to create a completely new Project, and copy all my code from the old project to the new one, just to eliminate the possibility that I had somehow accidentally corrupted my project files. I still have the same issue in my new project.
仅供参考：我尝试按照此处的另一个“xcode 链接器错误”线程中的描述搜索重复文件，但在我的项目中找不到任何重复文件。我还费心地创建了一个全新的项目，并将我所有的代码从旧项目复制到新项目，只是为了消除我以某种方式不小心损坏了项目文件的可能性。我在我的新项目中仍然有同样的问题。
Thanks
谢谢
回答by Sukhi
Add "CoreImage" framework.
添加“CoreImage”框架。
(Well, I know this question is old. But I had a same problem and adding "QuartzCore" framwork didn't help it).
（好吧，我知道这个问题很老。但我遇到了同样的问题，添加“QuartzCore”框架并没有帮助它）。
回答by Wevah
Make sure you've added the QuartzCore framework to your project (Linked Frameworks)!
确保您已将 QuartzCore 框架添加到您的项目（链接框架）中！
