Getting Strange Error Running Objective C Code

My project have no visible error but when i try to run it gives following error

Undefined symbols for architecture i386:
  "_OBJC_CLASS_$_ConcreteScreen", referenced from:
      objc-class-ref in ViewController.o
ld: symbol(s) not found for architecture i386
clang: error: linker command failed with exit code 1 (use -v to see invocation)

I am using my ContactScreen class in ViewController.m

i tried by @class ContactScree and #import "ContactScreen.h"

and in my ViewController i am using it as [ContactScreen myMethod]; when i comment out this line it work fine but now it is giving compile time error :( yesterday it was wroking fine

here is my code

#import "ViewController.h"

#import "ConcreteScreen.h"
@interface ViewController ()


@implementation ViewController

   NSLog(@"Contact Screen");

    ConcreteScreen *coontact = [[ConcreteScreen alloc]init];



You confused ConcreteScreen and ContactScreen and compiler told you that it isn't aware about ConcreteScreen

Be sure your .m file is included in the project. It's possible to create it, use the header and all but it doesn't go into the build. Also it needs to be in the target.

Need Your Help

PrimeFaces 3.5 and DataTables (multiple selection)

java primefaces datatable

I am currently experiencing a lot of troubles with the new release of PrimeFaces (3.5). Here's an example piece of code:

jquery serialize - get form field values issue

jquery serialization

I am using the serialize function to get the form field values. There is a text area in the form which accepts different values in a new line for e.g.