[Bug-IOS] - linker command failed with exit code 1 (use -v to see invocation)

Ld /Users/Rubert/Library/Developer/Xcode/DerivedData/OC_Language-emftyzftyvhdpuaxipddjmpnpvox/Build/Products/Debug/OC_Language normal x86_64

cd /Users/Rubert/IOS/iworkspace/OC_Language

export MACOSX_DEPLOYMENT_TARGET=10.10

/Applications/Xcode-beta.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang -arch x86_64 -isysroot /Applications/Xcode-beta.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.11.sdk -L/Users/Rubert/Library/Developer/Xcode/DerivedData/OC_Language-emftyzftyvhdpuaxipddjmpnpvox/Build/Products/Debug -F/Users/Rubert/Library/Developer/Xcode/DerivedData/OC_Language-emftyzftyvhdpuaxipddjmpnpvox/Build/Products/Debug -filelist /Users/Rubert/Library/Developer/Xcode/DerivedData/OC_Language-emftyzftyvhdpuaxipddjmpnpvox/Build/Intermediates/OC_Language.build/Debug/OC_Language.build/Objects-normal/x86_64/OC_Language.LinkFileList -mmacosx-version-min=10.10 -fobjc-arc -fobjc-link-runtime -Xlinker -dependency_info -Xlinker /Users/Rubert/Library/Developer/Xcode/DerivedData/OC_Language-emftyzftyvhdpuaxipddjmpnpvox/Build/Intermediates/OC_Language.build/Debug/OC_Language.build/Objects-normal/x86_64/OC_Language_dependency_info.dat -o /Users/Rubert/Library/Developer/Xcode/DerivedData/OC_Language-emftyzftyvhdpuaxipddjmpnpvox/Build/Products/Debug/OC_Language

duplicate symbol _OBJC_CLASS_$_Student in:

/Users/Rubert/Library/Developer/Xcode/DerivedData/OC_Language-emftyzftyvhdpuaxipddjmpnpvox/Build/Intermediates/OC_Language.build/Debug/OC_Language.build/Objects-normal/x86_64/main.o

/Users/Rubert/Library/Developer/Xcode/DerivedData/OC_Language-emftyzftyvhdpuaxipddjmpnpvox/Build/Intermediates/OC_Language.build/Debug/OC_Language.build/Objects-normal/x86_64/Student.o

duplicate symbol _OBJC_METACLASS_$_Student in:

/Users/Rubert/Library/Developer/Xcode/DerivedData/OC_Language-emftyzftyvhdpuaxipddjmpnpvox/Build/Intermediates/OC_Language.build/Debug/OC_Language.build/Objects-normal/x86_64/main.o

/Users/Rubert/Library/Developer/Xcode/DerivedData/OC_Language-emftyzftyvhdpuaxipddjmpnpvox/Build/Intermediates/OC_Language.build/Debug/OC_Language.build/Objects-normal/x86_64/Student.o

duplicate symbol _OBJC_IVAR_$_Student.s in:

/Users/Rubert/Library/Developer/Xcode/DerivedData/OC_Language-emftyzftyvhdpuaxipddjmpnpvox/Build/Intermediates/OC_Language.build/Debug/OC_Language.build/Objects-normal/x86_64/main.o

/Users/Rubert/Library/Developer/Xcode/DerivedData/OC_Language-emftyzftyvhdpuaxipddjmpnpvox/Build/Intermediates/OC_Language.build/Debug/OC_Language.build/Objects-normal/x86_64/Student.o

duplicate symbol _OBJC_IVAR_$_Student.age in:

/Users/Rubert/Library/Developer/Xcode/DerivedData/OC_Language-emftyzftyvhdpuaxipddjmpnpvox/Build/Intermediates/OC_Language.build/Debug/OC_Language.build/Objects-normal/x86_64/main.o

/Users/Rubert/Library/Developer/Xcode/DerivedData/OC_Language-emftyzftyvhdpuaxipddjmpnpvox/Build/Intermediates/OC_Language.build/Debug/OC_Language.build/Objects-normal/x86_64/Student.o

ld: 4 duplicate symbols for architecture x86_64

clang: error: linker command failed with exit code 1 (use -v to see invocation)

该问题主要是因为引用的头文件不对。

 #import <Foundation/Foundation.h>
 #import "Student.m"

 int main(int argc, const char * argv[]) {
    @autoreleasepool {
 //
 //
 ////1.基本类型()
 //NSLog(@"Hello, World!");
 //DataTypes_Clazz *stu = [[DataTypes_Clazz alloc] init];
 //[stu release];
 //2.基本语法

     //创建方式1
     Student *sPo = [Student alloc];
     sPo = [sPo init];
     [sPo setAge:()];
     NSLog(@"sPo.Age:%d",[sPo getAge]);

     //创建方式2
     Student *sPo2 = [[Student alloc] init];
     [sPo2 setAge:()];//设置值
     NSLog(@"sPo2.Age:%d",[sPo2 getAge]);

     //创建方式3
     //NSString *ns = [[NSString alloc] init];
     NSString *ns2 = @"";

    Student *sPo3 = [[Student alloc] initWithAge:() s:(ns2)];
    [sPo3 setAge:()];//设置值
    NSLog(@"sPo3.Age:%d",[sPo3 getAge]);
    NSLog(@"sPo3.S:%p",[sPo3 getS]);

    }

     return ;
 }

应该是#import "Student.h"，一不小心就犯了这个种低级错误。