title: NSTimer/NSTimeInterval
body: <p>Im trying to make a timer that counts down from 30 to 0 but this is the only way i could think to make it work, but it doesn't work. Anyone know what im doing wrong?</p>
  
  <p>.h file</p>
  
  <pre><code>@interface countDownAppViewController : UIViewController {
  
  UIButton *countDown;
  UILabel *displayThis;
  }
  
  @property (nonatomic, retain) IBOutlet UIButton *countDown;
  @property (nonatomic, retain) IBOutlet UILabel *displayThis;
  
  -(IBAction) theCount:(id) sender;
  -(IBAction) displayStuff:(id) sender;
  
  @end
  </code></pre>
  
  <p>.m file</p>
  
  <pre><code>@synthesize countDown;
  @synthesize displayThis;
  
  -(IBAction) theCount:(id) sender    {
  [NSTimer scheduledTimerWithTimeInterval:1.0
                                   target:self
                                 selector:@selector(displayStuff:)
                                 userInfo:nil
                                  repeats:NO];
  
  }
  int batman=30;
  -(void) viewDidLoad{
  
  displayThis.text = [NSString stringWithFormat:@"%i",batman];
  }
  
  -(IBAction) displayStuff:(id) sender    {
  while (batman &gt;= 0){
      batman--;
      [NSTimer scheduledTimerWithTimeInterval:1.0
                                       target:self
                                     selector:@selector(displayStuff:)
                                     userInfo:nil
                                      repeats:NO];
  displayThis.text = [NSString stringWithFormat:@"%i",batman];
  
  }
  }
  </code></pre>