title: sysctlbyname error Implicit declaration of function 'sysctlbyname' is invalid in C99
body: <p>I am getting an error "Implicit declaration of function 'sysctlbyname' is invalid in C99" when i used this code. I used it before and it was fine so I don't know what happen.</p>
  
  <p>I am currently developing for iOS7 devices only and using the latest ver of xcode 5 that is on the app store</p>
  
  <p>UIDeviceHardware.m</p>
  
  <pre><code>@interface UIDeviceHardware : NSObject
  
  - (NSString *) platform;
  - (NSString *) platformString;
  
  @end
  </code></pre>
  
  <p>UIDeviceHardware.m</p>
  
  <pre><code>- (NSString *) platform{
      size_t size;
      sysctlbyname("hw.machine", NULL, &amp;size, NULL, 0);
      char *machine = malloc(size);
      sysctlbyname("hw.machine", machine, &amp;size, NULL, 0);
      NSString *platform = [NSString stringWithUTF8String:machine];
      free(machine);
      return platform;
  }
  
  - (NSString *) platformString{
      NSString *platform = [self platform];
      if ([platform isEqualToString:@"iPhone1,1"])    return @"iPhone 1G";
      if ([platform isEqualToString:@"iPhone1,2"])    return @"iPhone 3G";
      if ([platform isEqualToString:@"iPhone2,1"])    return @"iPhone 3GS";
      if ([platform isEqualToString:@"iPhone3,1"])    return @"iPhone 4 (GSM)";
      if ([platform isEqualToString:@"iPhone3,3"])    return @"iPhone 4 (CDMA)";
      if ([platform isEqualToString:@"iPhone4,1"])    return @"iPhone 4S";
      if ([platform isEqualToString:@"iPhone5,1"])    return @"iPhone 5 (GSM)";
      if ([platform isEqualToString:@"iPhone5,2"])    return @"iPhone 5 (GSM+CDMA)";
      if ([platform isEqualToString:@"iPhone5,3"])    return @"iPhone 5c (GSM)";
      if ([platform isEqualToString:@"iPhone5,4"])    return @"iPhone 5c (GSM+CDMA)";
      if ([platform isEqualToString:@"iPhone6,1"])    return @"iPhone 5s (GSM)";
      if ([platform isEqualToString:@"iPhone6,2"])    return @"iPhone 5s (GSM+CDMA)";
      if ([platform isEqualToString:@"iPhone7,1"])    return @"iPhone 6 GSM";
      if ([platform isEqualToString:@"iPhone7,2"])    return @"iPhone 6 GSM+CDMA";
      if ([platform isEqualToString:@"iPhone8,1"])    return @"iPhone 6+ GSM";
      if ([platform isEqualToString:@"iPhone8,2"])    return @"iPhone 6+ Global";
      if ([platform isEqualToString:@"iPod1,1"])      return @"iPod Touch 1G";
      if ([platform isEqualToString:@"iPod2,1"])      return @"iPod Touch 2G";
      if ([platform isEqualToString:@"iPod3,1"])      return @"iPod Touch 3G";
      if ([platform isEqualToString:@"iPod4,1"])      return @"iPod Touch 4G";
      if ([platform isEqualToString:@"iPod5,1"])      return @"iPod Touch 5G";
      if ([platform isEqualToString:@"iPad1,1"])      return @"iPad";
      if ([platform isEqualToString:@"iPad2,1"])      return @"iPad 2 (WiFi)";
      if ([platform isEqualToString:@"iPad2,2"])      return @"iPad 2 (GSM)";
      if ([platform isEqualToString:@"iPad2,3"])      return @"iPad 2 (CDMA)";
      if ([platform isEqualToString:@"iPad2,4"])      return @"iPad 2 (WiFi)";
      if ([platform isEqualToString:@"iPad2,5"])      return @"iPad Mini (WiFi)";
      if ([platform isEqualToString:@"iPad2,6"])      return @"iPad Mini (GSM)";
      if ([platform isEqualToString:@"iPad2,7"])      return @"iPad Mini (GSM+CDMA)";
      if ([platform isEqualToString:@"iPad3,1"])      return @"iPad 3 (WiFi)";
      if ([platform isEqualToString:@"iPad3,2"])      return @"iPad 3 (GSM+CDMA)";
      if ([platform isEqualToString:@"iPad3,3"])      return @"iPad 3 (GSM)";
      if ([platform isEqualToString:@"iPad3,4"])      return @"iPad 4 (WiFi)";
      if ([platform isEqualToString:@"iPad3,5"])      return @"iPad 4 (GSM)";
      if ([platform isEqualToString:@"iPad3,6"])      return @"iPad 4 (GSM+CDMA)";
      if ([platform isEqualToString:@"iPad4,1"])      return @"iPad Air (WiFi)";
      if ([platform isEqualToString:@"iPad4,2"])      return @"iPad Air (GSM)";
      if ([platform isEqualToString:@"iPad4,4"])      return @"iPad Mini Retina (WiFi)";
      if ([platform isEqualToString:@"iPad4,5"])      return @"iPad Mini Retina (GSM)";
      if ([platform isEqualToString:@"i386"])         return @"Simulator";
      if ([platform isEqualToString:@"x86_64"])       return @"Simulator";
      return platform;
  }
  </code></pre>