Xcode error: "_main", referenced from: implicit entry/start for main executable

Question

I am getting the following error, which seems to be coming from something in the bottom to do with "_main".

Ld /Users/jianglin/Library/Developer/Xcode/DerivedData/TownHall_iPhone-bdlgipvgaapgjhglhromfvcubbxz/Build/Products/Debug-iphonesimulator/TownHall\ iPhone.app/TownHall\ iPhone normal i386
    cd "/Users/jianglin/Desktop/TownHall iPhone"
    export IPHONEOS_DEPLOYMENT_TARGET=8.1
    export PATH="/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/usr/bin:/Applications/Xcode.app/Contents/Developer/usr/bin:/usr/bin:/bin:/usr/sbin:/sbin"
    /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang -arch i386 -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator8.1.sdk -L/Users/jianglin/Library/Developer/Xcode/DerivedData/TownHall_iPhone-bdlgipvgaapgjhglhromfvcubbxz/Build/Products/Debug-iphonesimulator -F/Users/jianglin/Library/Developer/Xcode/DerivedData/TownHall_iPhone-bdlgipvgaapgjhglhromfvcubbxz/Build/Products/Debug-iphonesimulator -filelist /Users/jianglin/Library/Developer/Xcode/DerivedData/TownHall_iPhone-bdlgipvgaapgjhglhromfvcubbxz/Build/Intermediates/TownHall\ iPhone.build/Debug-iphonesimulator/TownHall\ iPhone.build/Objects-normal/i386/TownHall\ iPhone.LinkFileList -Xlinker -rpath -Xlinker @executable_path/Frameworks -Xlinker -objc_abi_version -Xlinker 2 -ObjC -lPods-AFNetworking -lPods-Masonry -lPods-SDWebImage -framework CoreGraphics -framework Foundation -framework ImageIO -framework MobileCoreServices -framework Security -framework SystemConfiguration -framework UIKit -fobjc-arc -fobjc-link-runtime -Xlinker -no_implicit_dylibs -mios-simulator-version-min=8.1 -lPods -Xlinker -dependency_info -Xlinker /Users/jianglin/Library/Developer/Xcode/DerivedData/TownHall_iPhone-bdlgipvgaapgjhglhromfvcubbxz/Build/Intermediates/TownHall\ iPhone.build/Debug-iphonesimulator/TownHall\ iPhone.build/Objects-normal/i386/TownHall\ iPhone_dependency_info.dat -o /Users/jianglin/Library/Developer/Xcode/DerivedData/TownHall_iPhone-bdlgipvgaapgjhglhromfvcubbxz/Build/Products/Debug-iphonesimulator/TownHall\ iPhone.app/TownHall\ iPhone

Undefined symbols for architecture i386:
  "_main", referenced from:
     implicit entry/start for main executable
     (maybe you meant: _OBJC_IVAR_$_PostTableViewCell._mainTextView, _OBJC_IVAR_$_ConfirmationViewController._mainLabel , _OBJC_IVAR_$_SignInViewController._mainLabel , _OBJC_IVAR_$_SignUpViewController._mainLabel )
ld: symbol(s) not found for architecture i386
clang: error: linker command failed with exit code 1 (use -v to see invocation)

Any help would be much appreciated.

Answer 1

I checked your project. The issue is simple, in your project there is no main.m file. I think you accidentally deleted that.

Add a new .m file to your project, name it as main

And add the following code to it:

#import <UIKit/UIKit.h>
#import "AppDelegate.h"

int main(int argc, char * argv[]) {
    @autoreleasepool {
        return UIApplicationMain(argc, argv, nil, NSStringFromClass([AppDelegate class]));
    }
}

Also in your project the info.plist is also missing, so you need to add a new one.

Answer 2

add @UIApplicationMain to the AppDelegate

Answer 3

My case was very similar, but slightly different. The solution was in part prompted by @Midhun-MP's answer above.

In my instance, I had added a tvOS version of my app. After adding the new target however, main.m was not selected under Target Membership (thus, the warning messages about Undefined symbols for architecture x86_64: "_main"). Checked that off and bam -- I'm GTG.

Thanks @Midhun-MP.