（如果你有想法，无论是什么，请发布答案，即使它不能解决我的问题，我也会给你+1：）
刚刚收到这个错误。
我在谷歌上搜索了一下，到目前为止还没有找到解决方案。
链接器命令失败，退出代码为1（使用-v查看调用）体系结构x86_64 的重复符号
clang:错误：链接器命令失败，退出代码为1（使用-v查看调用）_game 的重复符号_sprites
链接器命令失败，退出代码为1（使用-v查看调用），体系结构的符号未定义
Ld /Users/TLL/Library/Developer/Xcode/DerivedData/AFDateHelperExtObjective-C-drnbulhrpdtwsbctmtvxzbnfjavn/Build/Products/Debug-iphonesimulator/AFDateHelperExtObjective-C.app/AFDateHelperExtObjective-C normal x86_64
cd "/Users/TLL/Desktop/iOS Learn/Objective-C Mark Price Udemy/Ex 6 AFDateHelper /AFDateHelperExtObjective-C"
export IPHONEOS_DEPLOYMENT_TARGET=9.2
export PATH="/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/usr/bin:/Applications/Xcode.app/Contents/Developer/usr/bin:/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin"
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang -arch x86_64 -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator9.2.sdk -L/Users/TLL/Library/Developer/Xcode/DerivedData/AFDateHelperExtObjective-C-drnbulhrpdtwsbctmtvxzbnfjavn/Build/Products/Debug-iphonesimulator -F/Users/TLL/Library/Developer/Xcode/DerivedData/AFDateHelperExtObjective-C-drnbulhrpdtwsbctmtvxzbnfjavn/Build/Products/Debug-iphonesimulator -filelist /Users/TLL/Library/Developer/Xcode/DerivedData/AFDateHelperExtObjective-C-drnbulhrpdtwsbctmtvxzbnfjavn/Build/Intermediates/AFDateHelperExtObjective-C.build/Debug-iphonesimulator/AFDateHelperExtObjective-C.build/Objects-normal/x86_64/AFDateHelperExtObjective-C.LinkFileList -Xlinker -rpath -Xlinker @executable_path/Frameworks -mios-simulator-version-min=9.2 -Xlinker -objc_abi_version -Xlinker 2 -fobjc-arc -fobjc-link-runtime -Xlinker -dependency_info -Xlinker /Users/TLL/Library/Developer/Xcode/DerivedData/AFDateHelperExtObjective-C-drnbulhrpdtwsbctmtvxzbnfjavn/Build/Intermediates/AFDateHelperExtObjective-C.build/Debug-iphonesimulator/AFDateHelperExtObjective-C.build/Objects-normal/x86_64/AFDateHelperExtObjective-C_dependency_info.dat -o /Users/TLL/Library/Developer/Xcode/DerivedData/AFDateHelperExtObjective-C-drnbulhrpdtwsbctmtvxzbnfjavn/Build/Products/Debug-iphonesimulator/AFDateHelperExtObjective-C.app/AFDateHelperExtObjective-C
duplicate symbol _ISOFormatYear in:
/Users/TLL/Library/Developer/Xcode/DerivedData/AFDateHelperExtObjective-C-drnbulhrpdtwsbctmtvxzbnfjavn/Build/Intermediates/AFDateHelperExtObjective-C.build/Debug-iphonesimulator/AFDateHelperExtObjective-C.build/Objects-normal/x86_64/ViewController.o
/Users/TLL/Library/Developer/Xcode/DerivedData/AFDateHelperExtObjective-C-drnbulhrpdtwsbctmtvxzbnfjavn/Build/Intermediates/AFDateHelperExtObjective-C.build/Debug-iphonesimulator/AFDateHelperExtObjective-C.build/Objects-normal/x86_64/NSDate+AFDateHelperObjC.o
duplicate symbol _ISOFormatYearMonth in:
/Users/TLL/Library/Developer/Xcode/DerivedData/AFDateHelperExtObjective-C-drnbulhrpdtwsbctmtvxzbnfjavn/Build/Intermediates/AFDateHelperExtObjective-C.build/Debug-iphonesimulator/AFDateHelperExtObjective-C.build/Objects-normal/x86_64/ViewController.o
/Users/TLL/Library/Developer/Xcode/DerivedData/AFDateHelperExtObjective-C-drnbulhrpdtwsbctmtvxzbnfjavn/Build/Intermediates/AFDateHelperExtObjective-C.build/Debug-iphonesimulator/AFDateHelperExtObjective-C.build/Objects-normal/x86_64/NSDate+AFDateHelperObjC.o
duplicate symbol _ISOFormatDate in:
/Users/TLL/Library/Developer/Xcode/DerivedData/AFDateHelperExtObjective-C-drnbulhrpdtwsbctmtvxzbnfjavn/Build/Intermediates/AFDateHelperExtObjective-C.build/Debug-iphonesimulator/AFDateHelperExtObjective-C.build/Objects-normal/x86_64/ViewController.o
/Users/TLL/Library/Developer/Xcode/DerivedData/AFDateHelperExtObjective-C-drnbulhrpdtwsbctmtvxzbnfjavn/Build/Intermediates/AFDateHelperExtObjective-C.build/Debug-iphonesimulator/AFDateHelperExtObjective-C.build/Objects-normal/x86_64/NSDate+AFDateHelperObjC.o
duplicate symbol _DotNetDateFormatType in:
/Users/TLL/Library/Developer/Xcode/DerivedData/AFDateHelperExtObjective-C-drnbulhrpdtwsbctmtvxzbnfjavn/Build/Intermediates/AFDateHelperExtObjective-C.build/Debug-iphonesimulator/AFDateHelperExtObjective-C.build/Objects-normal/x86_64/ViewController.o
/Users/TLL/Library/Developer/Xcode/DerivedData/AFDateHelperExtObjective-C-drnbulhrpdtwsbctmtvxzbnfjavn/Build/Intermediates/AFDateHelperExtObjective-C.build/Debug-iphonesimulator/AFDateHelperExtObjective-C.build/Objects-normal/x86_64/NSDate+AFDateHelperObjC.o
duplicate symbol _CustomDateFormatType in:
/Users/TLL/Library/Developer/Xcode/DerivedData/AFDateHelperExtObjective-C-drnbulhrpdtwsbctmtvxzbnfjavn/Build/Intermediates/AFDateHelperExtObjective-C.build/Debug-iphonesimulator/AFDateHelperExtObjective-C.build/Objects-normal/x86_64/ViewController.o
/Users/TLL/Library/Developer/Xcode/DerivedData/AFDateHelperExtObjective-C-drnbulhrpdtwsbctmtvxzbnfjavn/Build/Intermediates/AFDateHelperExtObjective-C.build/Debug-iphonesimulator/AFDateHelperExtObjective-C.build/Objects-normal/x86_64/NSDate+AFDateHelperObjC.o
duplicate symbol _AltRSSDateFormatType in:
/Users/TLL/Library/Developer/Xcode/DerivedData/AFDateHelperExtObjective-C-drnbulhrpdtwsbctmtvxzbnfjavn/Build/Intermediates/AFDateHelperExtObjective-C.build/Debug-iphonesimulator/AFDateHelperExtObjective-C.build/Objects-normal/x86_64/ViewController.o
/Users/TLL/Library/Developer/Xcode/DerivedData/AFDateHelperExtObjective-C-drnbulhrpdtwsbctmtvxzbnfjavn/Build/Intermediates/AFDateHelperExtObjective-C.build/Debug-iphonesimulator/AFDateHelperExtObjective-C.build/Objects-normal/x86_64/NSDate+AFDateHelperObjC.o
duplicate symbol _RSSDateFormatType in:
/Users/TLL/Library/Developer/Xcode/DerivedData/AFDateHelperExtObjective-C-drnbulhrpdtwsbctmtvxzbnfjavn/Build/Intermediates/AFDateHelperExtObjective-C.build/Debug-iphonesimulator/AFDateHelperExtObjective-C.build/Objects-normal/x86_64/ViewController.o
/Users/TLL/Library/Developer/Xcode/DerivedData/AFDateHelperExtObjective-C-drnbulhrpdtwsbctmtvxzbnfjavn/Build/Intermediates/AFDateHelperExtObjective-C.build/Debug-iphonesimulator/AFDateHelperExtObjective-C.build/Objects-normal/x86_64/NSDate+AFDateHelperObjC.o
duplicate symbol _ISO8601DateFormatType in:
/Users/TLL/Library/Developer/Xcode/DerivedData/AFDateHelperExtObjective-C-drnbulhrpdtwsbctmtvxzbnfjavn/Build/Intermediates/AFDateHelperExtObjective-C.build/Debug-iphonesimulator/AFDateHelperExtObjective-C.build/Objects-normal/x86_64/ViewController.o
/Users/TLL/Library/Developer/Xcode/DerivedData/AFDateHelperExtObjective-C-drnbulhrpdtwsbctmtvxzbnfjavn/Build/Intermediates/AFDateHelperExtObjective-C.build/Debug-iphonesimulator/AFDateHelperExtObjective-C.build/Objects-normal/x86_64/NSDate+AFDateHelperObjC.o
duplicate symbol _ISOFormatDateTime in:
/Users/TLL/Library/Developer/Xcode/DerivedData/AFDateHelperExtObjective-C-drnbulhrpdtwsbctmtvxzbnfjavn/Build/Intermediates/AFDateHelperExtObjective-C.build/Debug-iphonesimulator/AFDateHelperExtObjective-C.build/Objects-normal/x86_64/ViewController.o
/Users/TLL/Library/Developer/Xcode/DerivedData/AFDateHelperExtObjective-C-drnbulhrpdtwsbctmtvxzbnfjavn/Build/Intermediates/AFDateHelperExtObjective-C.build/Debug-iphonesimulator/AFDateHelperExtObjective-C.build/Objects-normal/x86_64/NSDate+AFDateHelperObjC.o
duplicate symbol _ISOFormatDateTimeMilliSec in:
/Users/TLL/Library/Developer/Xcode/DerivedData/AFDateHelperExtObjective-C-drnbulhrpdtwsbctmtvxzbnfjavn/Build/Intermediates/AFDateHelperExtObjective-C.build/Debug-iphonesimulator/AFDateHelperExtObjective-C.build/Objects-normal/x86_64/ViewController.o
/Users/TLL/Library/Developer/Xcode/DerivedData/AFDateHelperExtObjective-C-drnbulhrpdtwsbctmtvxzbnfjavn/Build/Intermediates/AFDateHelperExtObjective-C.build/Debug-iphonesimulator/AFDateHelperExtObjective-C.build/Objects-normal/x86_64/NSDate+AFDateHelperObjC.o
duplicate symbol _ISOFormatDateTimeSec in:
/Users/TLL/Library/Developer/Xcode/DerivedData/AFDateHelperExtObjective-C-drnbulhrpdtwsbctmtvxzbnfjavn/Build/Intermediates/AFDateHelperExtObjective-C.build/Debug-iphonesimulator/AFDateHelperExtObjective-C.build/Objects-normal/x86_64/ViewController.o
/Users/TLL/Library/Developer/Xcode/DerivedData/AFDateHelperExtObjective-C-drnbulhrpdtwsbctmtvxzbnfjavn/Build/Intermediates/AFDateHelperExtObjective-C.build/Debug-iphonesimulator/AFDateHelperExtObjective-C.build/Objects-normal/x86_64/NSDate+AFDateHelperObjC.o
duplicate symbol _ISOFormatYear in:
/Users/TLL/Library/Developer/Xcode/DerivedData/AFDateHelperExtObjective-C-drnbulhrpdtwsbctmtvxzbnfjavn/Build/Intermediates/AFDateHelperExtObjective-C.build/Debug-iphonesimulator/AFDateHelperExtObjective-C.build/Objects-normal/x86_64/ViewController.o
/Users/TLL/Library/Developer/Xcode/DerivedData/AFDateHelperExtObjective-C-drnbulhrpdtwsbctmtvxzbnfjavn/Build/Intermediates/AFDateHelperExtObjective-C.build/Debug-iphonesimulator/AFDateHelperExtObjective-C.build/Objects-normal/x86_64/DateFormat.o
duplicate symbol _ISOFormatYearMonth in:
/Users/TLL/Library/Developer/Xcode/DerivedData/AFDateHelperExtObjective-C-drnbulhrpdtwsbctmtvxzbnfjavn/Build/Intermediates/AFDateHelperExtObjective-C.build/Debug-iphonesimulator/AFDateHelperExtObjective-C.build/Objects-normal/x86_64/ViewController.o
/Users/TLL/Library/Developer/Xcode/DerivedData/AFDateHelperExtObjective-C-drnbulhrpdtwsbctmtvxzbnfjavn/Build/Intermediates/AFDateHelperExtObjective-C.build/Debug-iphonesimulator/AFDateHelperExtObjective-C.build/Objects-normal/x86_64/DateFormat.o
duplicate symbol _ISOFormatDate in:
/Users/TLL/Library/Developer/Xcode/DerivedData/AFDateHelperExtObjective-C-drnbulhrpdtwsbctmtvxzbnfjavn/Build/Intermediates/AFDateHelperExtObjective-C.build/Debug-iphonesimulator/AFDateHelperExtObjective-C.build/Objects-normal/x86_64/ViewController.o
/Users/TLL/Library/Developer/Xcode/DerivedData/AFDateHelperExtObjective-C-drnbulhrpdtwsbctmtvxzbnfjavn/Build/Intermediates/AFDateHelperExtObjective-C.build/Debug-iphonesimulator/AFDateHelperExtObjective-C.build/Objects-normal/x86_64/DateFormat.o
duplicate symbol _DotNetDateFormatType in:
/Users/TLL/Library/Developer/Xcode/DerivedData/AFDateHelperExtObjective-C-drnbulhrpdtwsbctmtvxzbnfjavn/Build/Intermediates/AFDateHelperExtObjective-C.build/Debug-iphonesimulator/AFDateHelperExtObjective-C.build/Objects-normal/x86_64/ViewController.o
/Users/TLL/Library/Developer/Xcode/DerivedData/AFDateHelperExtObjective-C-drnbulhrpdtwsbctmtvxzbnfjavn/Build/Intermediates/AFDateHelperExtObjective-C.build/Debug-iphonesimulator/AFDateHelperExtObjective-C.build/Objects-normal/x86_64/DateFormat.o
duplicate symbol _CustomDateFormatType in:
/Users/TLL/Library/Developer/Xcode/DerivedData/AFDateHelperExtObjective-C-drnbulhrpdtwsbctmtvxzbnfjavn/Build/Intermediates/AFDateHelperExtObjective-C.build/Debug-iphonesimulator/AFDateHelperExtObjective-C.build/Objects-normal/x86_64/ViewController.o
/Users/TLL/Library/Developer/Xcode/DerivedData/AFDateHelperExtObjective-C-drnbulhrpdtwsbctmtvxzbnfjavn/Build/Intermediates/AFDateHelperExtObjective-C.build/Debug-iphonesimulator/AFDateHelperExtObjective-C.build/Objects-normal/x86_64/DateFormat.o
duplicate symbol _AltRSSDateFormatType in:
/Users/TLL/Library/Developer/Xcode/DerivedData/AFDateHelperExtObjective-C-drnbulhrpdtwsbctmtvxzbnfjavn/Build/Intermediates/AFDateHelperExtObjective-C.build/Debug-iphonesimulator/AFDateHelperExtObjective-C.build/Objects-normal/x86_64/ViewController.o
/Users/TLL/Library/Developer/Xcode/DerivedData/AFDateHelperExtObjective-C-drnbulhrpdtwsbctmtvxzbnfjavn/Build/Intermediates/AFDateHelperExtObjective-C.build/Debug-iphonesimulator/AFDateHelperExtObjective-C.build/Objects-normal/x86_64/DateFormat.o
duplicate symbol _RSSDateFormatType in:
/Users/TLL/Library/Developer/Xcode/DerivedData/AFDateHelperExtObjective-C-drnbulhrpdtwsbctmtvxzbnfjavn/Build/Intermediates/AFDateHelperExtObjective-C.build/Debug-iphonesimulator/AFDateHelperExtObjective-C.build/Objects-normal/x86_64/ViewController.o
/Users/TLL/Library/Developer/Xcode/DerivedData/AFDateHelperExtObjective-C-drnbulhrpdtwsbctmtvxzbnfjavn/Build/Intermediates/AFDateHelperExtObjective-C.build/Debug-iphonesimulator/AFDateHelperExtObjective-C.build/Objects-normal/x86_64/DateFormat.o
duplicate symbol _ISO8601DateFormatType in:
/Users/TLL/Library/Developer/Xcode/DerivedData/AFDateHelperExtObjective-C-drnbulhrpdtwsbctmtvxzbnfjavn/Build/Intermediates/AFDateHelperExtObjective-C.build/Debug-iphonesimulator/AFDateHelperExtObjective-C.build/Objects-normal/x86_64/ViewController.o
/Users/TLL/Library/Developer/Xcode/DerivedData/AFDateHelperExtObjective-C-drnbulhrpdtwsbctmtvxzbnfjavn/Build/Intermediates/AFDateHelperExtObjective-C.build/Debug-iphonesimulator/AFDateHelperExtObjective-C.build/Objects-normal/x86_64/DateFormat.o
duplicate symbol _ISOFormatDateTime in:
/Users/TLL/Library/Developer/Xcode/DerivedData/AFDateHelperExtObjective-C-drnbulhrpdtwsbctmtvxzbnfjavn/Build/Intermediates/AFDateHelperExtObjective-C.build/Debug-iphonesimulator/AFDateHelperExtObjective-C.build/Objects-normal/x86_64/ViewController.o
/Users/TLL/Library/Developer/Xcode/DerivedData/AFDateHelperExtObjective-C-drnbulhrpdtwsbctmtvxzbnfjavn/Build/Intermediates/AFDateHelperExtObjective-C.build/Debug-iphonesimulator/AFDateHelperExtObjective-C.build/Objects-normal/x86_64/DateFormat.o
duplicate symbol _ISOFormatDateTimeMilliSec in:
/Users/TLL/Library/Developer/Xcode/DerivedData/AFDateHelperExtObjective-C-drnbulhrpdtwsbctmtvxzbnfjavn/Build/Intermediates/AFDateHelperExtObjective-C.build/Debug-iphonesimulator/AFDateHelperExtObjective-C.build/Objects-normal/x86_64/ViewController.o
/Users/TLL/Library/Developer/Xcode/DerivedData/AFDateHelperExtObjective-C-drnbulhrpdtwsbctmtvxzbnfjavn/Build/Intermediates/AFDateHelperExtObjective-C.build/Debug-iphonesimulator/AFDateHelperExtObjective-C.build/Objects-normal/x86_64/DateFormat.o
duplicate symbol _ISOFormatDateTimeSec in:
/Users/TLL/Library/Developer/Xcode/DerivedData/AFDateHelperExtObjective-C-drnbulhrpdtwsbctmtvxzbnfjavn/Build/Intermediates/AFDateHelperExtObjective-C.build/Debug-iphonesimulator/AFDateHelperExtObjective-C.build/Objects-normal/x86_64/ViewController.o
/Users/TLL/Library/Developer/Xcode/DerivedData/AFDateHelperExtObjective-C-drnbulhrpdtwsbctmtvxzbnfjavn/Build/Intermediates/AFDateHelperExtObjective-C.build/Debug-iphonesimulator/AFDateHelperExtObjective-C.build/Objects-normal/x86_64/DateFormat.o
ld: 22 duplicate symbols for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
到目前为止我尝试了什么：
- 我没有发现重复的申报单
- 我在某个地方没有发现错误的导入".h"或".m"
- 在生成设置中未使用"-Oj-C"
我的日期格式.h:
#import <Foundation/Foundation.h>
NSString * const ISO8601DateFormatType = @"ISO8601";
NSString * const DotNetDateFormatType = @"DotNet";
NSString * const RSSDateFormatType = @"RSS";
NSString * const AltRSSDateFormatType = @"AltRSS";
NSString * const CustomDateFormatType = @"Custom";
NSString * const ISOFormatYear = @"yyyy";
NSString * const ISOFormatYearMonth = @"yyyy-MM"; // 1997-07
NSString * const ISOFormatDate = @"yyyy-MM-dd"; // 1997-07-16
NSString * const ISOFormatDateTime = @"yyyy-MM-dd'T'HH:mmZ"; // 1997-07-16T19:20+01:00
NSString * const ISOFormatDateTimeSec = @"yyyy-MM-dd'T'HH:mm:ssZ"; // 1997-07-16T19:20:30+01:00
NSString * const ISOFormatDateTimeMilliSec = @"yyyy-MM-dd'T'HH:mm:ss.SSSZ"; // 1997-07-16T19:20:30.45+01:00
@interface DateFormat : NSObject
+ (instancetype) ISODateFormat: (NSString *) isoFormat;
+ (instancetype) DotNetDateFormat;
+ (instancetype) RSSDateFormat;
+ (instancetype) AltRSSDateFormat;
+ (instancetype) CustomDateFormat: (NSString *) formatString;
@property (readonly) NSString *dateFormatType;
@property (readonly) NSString *formatDetails;
@end
您已经在.h中使用：声明了字符串
NSString * const ...
这意味着每个导入.h的文件都声明了相同的一组字符串，最终会出现重复的符号。
您可以通过在.h extern中进行每个声明来解决这个问题，这意味着它只是声明在其他地方定义的变量的名称和类型，并删除初始化；然后在相应的CCD_ 5中包括没有CCD_。
另一种更短但更丑陋的解决方案是在.h static中进行所有声明，并保留初始化。这种方法为每个包含.h的.m提供了自己的私有变量集。空间上有点浪费，但其他方面都很好。
HTH
您似乎已经两次添加了对AFDateHelper的引用（以及NSDate上的一个附带类别）。有时清洁可以解决这个问题。如果没有，则在导航器中选择该文件（AFDateHelper.m），取消选中其目标成员资格，然后尝试再次构建。如果它生成了，那么项目中的其他地方就会有对该文件的第二个引用。最佳