title: how to tab from text field 1 to text field 2 by pressing button
body: <p>I am trying to make a calculator app for iphone 
  so now i finished all operations and i want to make if the user typed in the text field his first number and then if he tapped the '+' button i want the test field switch or tab to the another text field </p>
  
  <p>so how can i do it ?
  here is the header </p>
  
  <pre><code>    #import &lt;UIKit/UIKit.h&gt;
  @interface ViewController : UIViewController
  {
      int a,b,c;
      char op;
      UILabel*operation,*result;
      UITextField *num1,*num2;  
  }
  @property (nonatomic)int a , b ,c;
  @property (nonatomic)char po;
  @property (nonatomic ,retain)IBOutlet UILabel*operation,*result;
  @property (nonatomic ,retain)IBOutlet UITextField *num1,*num2;;
  
  -(IBAction)sum:(id)sender;
  -(IBAction)Calculate:(id)sender;
  -(IBAction)Clear:(id)sender;
  -(IBAction)hideKeyboard:(id)sender;
  @end
  </code></pre>
  
  <p>.m file </p>
  
  <pre><code>#import "ViewController.h"
  
  @interface ViewController ()
  
  @end
  
  @implementation ViewController
  @synthesize operation,result,num1,num2,a,b,c,po;
  -(IBAction)sum:(id)sender{
      operation.text=@"+";
  
  
  }
  -(IBAction)hideKeyboard:(id)sender{
      [num1 resignFirstResponder];   
      [num2 resignFirstResponder];
  }
  -(IBAction)Calculate:(id)sender{
  
      //sum
      a =num1.text.integerValue;
      b= num2.text.integerValue;
      c=num1.text.integerValue+num2.text.integerValue;
      printf("%i &gt;&gt; %i",b,num2.text.integerValue);
      [num1 resignFirstResponder];
      [num2 resignFirstResponder];
      result.text =[NSString stringWithFormat:@"%i + %i = %i",a,b,c];
  
  
  
  }
  -(IBAction)Clear:(id)sender{
      [num1 resignFirstResponder];
      [num2 resignFirstResponder];
      num1.text=@"";
      num2.text=@"";
      operation.text=@"";
      a=0;
      b=0;
      c=0;
      result.text=@"";
      op=' ';
  
  }
  </code></pre>