ios - Objective-C构建中的重复符号错误？

Question

按 build+debug 时出现此错误：

ld: duplicate symbol .objc_class_name_BlogTableItemCell in /Users/fabian/Development/Workspaces/iphone_experiments/xcode_build_output/MausLog.build/Debug-iphonesimulator/MausLog.build/Objects-normal/i386/BlogTableItemCell-3733583914888A7B.o and /Users/fabian/Development/Workspaces/iphone_experiments/xcode_build_output/MausLog.build/Debug-iphonesimulator/MausLog.build/Objects-normal/i386/BlogTableItemCell-3733583914888A7B.o
collect2: ld returned 1 exit status
Command /Developer/Platforms/iPhoneSimulator.platform/Developer/usr/bin/gcc-4.2 failed with exit code 1

score 176 · Accepted Answer

如果您错误地让 Xcode 的 #import 语句自动完成功能为 'duplicate' 类指定了 '.m" 文件而不是 '.h'，也可能会出现此错误。

score 64 · Accepted Answer

您似乎在代码的不同位置两次编译相同的 BlogTableItemCell 类。在以下情况下可能会发生这种情况。

您已将相同的类实现放入两个不同的文件中；
您实际上只有一个此类的实现，但是您还在项目中链接了一个框架或库，其中包含一个与您的名称完全相同的类。

尝试在整个项目中找到您的班级，并确保您的项目中只有一份可用。

score 43 · Accepted Answer

For me, changing 'No Common Blocks' from Yes to No ( under Targets->Build Settings->Apple LLVM - Code Generation ) enter image description here

score 25 · Accepted Answer

由于 const 定义不佳，我遇到了类似的问题。我在标题中定义了一个 const：

int const kCropLocationTop = 1;

这大概是多次进口的。为了解决这个问题，我更改了标题 def 如下：

extern int const kCropLocationTop;

并将 const 的分配移至 .m 文件：

int const kCropLocationTop = 1;

希望对像我一样对简单的客观 c 概念一无所知的人有所帮助！

score 18 · Accepted Answer

iPhone：重复符号错误？由用户576924

为我正确回答。但是要找到这个 ZSH 片段有问题的 gremlin。

grep "import.*\.m" **/*.[hm]

会立即告诉你你的错误在哪里。

score 18 · Accepted Answer

By mistake the source file was included twice in the Project -> Build Phase -> Compile Sources. Removing one of them solved the problem.

score 9 · Accepted Answer

The most common reason for this error is importing an xyz.m file instead of the xyz.h file. Check if your imports contain something like #import "----.m"

score 4 · Accepted Answer

Just to add; Using Xcode to generate subclassed managed objects (Core Data) can sometimes duplicate the generated files. For me the fix was to delete the generated files and re-generate them.

score 3 · Accepted Answer

我自己也遇到了这个问题。对于列表，这是另一种可能性：

项目文件中的重复链接行。

当我不小心复制了一行时，我在 SVN 更新中引起了这种合并冲突。

score 2 · Accepted Answer

It happened to me, too. In my case, one (just one) of my core data automatically generated classes was inserted twice. I spotted the duplication by looking at Build Phases...Compile Sources. Simply deleting one of the occurrences solved the problem.

score 2 · Accepted Answer

Adding another possible cause to the list... you may have mistakingly created multiple constants in the implementation file, but outside of the implementation, with the same name.

In HeaderFileOne.m

NSString * const kCoolConstant = @"cool";

In HeaderFileTwo.m

NSString * const kCoolConstant = @"cool";

So changing one of those constant names would fix the compile error.

score 2 · Accepted Answer

This may help someone

I got this error because I duplicate a ViewController and then renamed it. So when I compile I got this error. The reason was in both of the view controllers there was a "float" variable with same name i.e "float padding=10.0" which I had defined on class level. Renaming the name of the above mentioned variable in One of the view controllers solved my problem.

score 1 · Accepted Answer

I also faced to this problem. My solution was rename one of global variable, which has the same name as one in other class. Hope this helps

score 0 · Accepted Answer

The same thing happened to me while I was playing with localizable xib files, accidentally I have created two implementation files and appereantly that caused the problem in my case. After deleting / recreating the implementation file without doing the same mistake, the error was fixed.

score 0 · Accepted Answer

One of our developers left the "libSoomla*" project files in there twice. I removed the duplicate soomla files, re-built, and that fixed it!

Hope it helps.

score 0 · Accepted Answer

In may case, I followed some instructions to build a newer version of Subversion which directed me to create this symbolic link:

ln -s /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/ /Applications/Xcode.app/Contents/Developer/Toolchains/OSX10.10.xctoolchain

Now I'm really a Windows guy so it wasn't immediately obvious to me - but removing the link fixed it for me (after restarting XCode):

rm /Applications/Xcode.app/Contents/Developer/Toolchains/OSX10.10.xctoolchain

Phew.

(The actual error I got was the one described here: build error duplicate symbols arclite.o)

score 0 · Accepted Answer

Make sure that you didn't import .m File . For me this happen I added #import "SchoolCommuterHome.m" instead of #import "SchoolCommuterHome.h"

ios - Objective-C构建中的重复符号错误？

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