add a countdown, display the time and fire an action - iphone

Question

Hi I am a beginner in programming
I have already created a tapping application, displaying the tap count after pressing the result button
I want to add a NSTimer, counting 30 second after the first tap (after the tap button was pressed for the first time).
at the same time, displaying the time count down on a label (UILabel timeLabel)
and after 30 second, the tap count will restart to 0.
Please kindly tell me if I need to post anything other than the following, Thanks!!
Here is my .h file
#import <UIKit/UIKit.h>
#import <AVFoundation/AVAudioPlayer.h>
#import <AudioToolbox/AudioToolbox.h>
#class Player;
#interface Tapping2ViewController : UIViewController
<AVAudioPlayerDelegate>
{
Player *aPlayer;
IBOutlet UILabel *timerLabel;
IBOutlet UILabel *resultLabel;
AVAudioPlayer *buttonPlayer;
NSTimer *lv1Timer;
NSInteger *counter1;
}
- (IBAction)addTap:(id)sender;
- (IBAction)getResult:(id)sender;
-(void)restartTapCount;
-(void)start;
#property (retain) NSTimer *lv1Timer;
#property (nonatomic, retain) IBOutlet UILabel *timerLabel;
#end
and my .M file
#import "Tapping2ViewController.h"
#import "Player.h"
#implementation Tapping2ViewController
#synthesize lv1Timer;
#synthesize timerLabel;
- (id) initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
self = [super initWithNibName:nibNameOrNil
bundle:nibBundleOrNil];
if (self) {
}
return self;
}
- (void)dealloc
{
[resultLabel release];
[lv1Timer release];
[aPlayer release];
[timerLabel release];
[super dealloc];
}
- (void)didReceiveMemoryWarning
{
// Releases the view if it doesn't have a superview.
[super didReceiveMemoryWarning];
// Release any cached data, images, etc that aren't in use.
}
#pragma mark - View lifecycle
- (void)viewDidLoad
{
aPlayer = [[Player alloc] init];
[super viewDidLoad];
}
- (IBAction)addTap:(id)sender
{
//呢到係設定聲音， 首先要用NSSTRING 去 SET 左條路徑先
NSString *buttonFile = [[NSBundle mainBundle] pathForResource:#"button" ofType:#"wav"];
//之後再條NSSTRING 轉做NSURL （因為AVPLAYER 只認URL）
NSURL *buttonFileURL = [NSURL fileURLWithPath:buttonFile];
NSError *error = nil;
//設定AUDIO PLAYER 要播邊條 聲音 ＊記得SET DELEGATE 做自已去執行
buttonPlayer = [[AVAudioPlayer alloc] initWithContentsOfURL:buttonFileURL error:&error];
[buttonPlayer setDelegate:self];
NSLog(#"Before: %d", aPlayer.tapCount);
aPlayer.tapCount++;
//呼叫播放既METHOD
[buttonPlayer play];
NSLog(#"After: %d", aPlayer.tapCount);
/*
//即時顯示數字
aPlayer.result = aPlayer.tapCount;
NSString *sResult = [NSString stringWithFormat:#"%D", aPlayer.result];
resultLabel.text = sResult;
*/
}
- (IBAction)getResult:(id)sender {
aPlayer.result = aPlayer.tapCount;
NSString *aResult = [NSString stringWithFormat:#"%D", aPlayer.result];
resultLabel.text = aResult;
}
-(void)motionEnded:(UIEventSubtype)motion withEvent:(UIEvent *)event
{
if (motion == UIEventSubtypeMotionShake)
{
aPlayer.tapCount = 0;
resultLabel.text = #"0";
}
}
- (void)viewDidUnload
{
[resultLabel release];
resultLabel = nil;
[timerLabel release];
timerLabel = nil;
[super viewDidUnload];
// Release any retained subviews of the main view.
// e.g. self.myOutlet = nil;
}
- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
// Return YES for supported orientations
return (interfaceOrientation == UIInterfaceOrientationPortrait);
}
//下面係PART OF DETECT SHAKE 既METHOD
-(BOOL)canBecomeFirstResponder
{
return YES;
}
-(void)viewDidAppear:(BOOL)animated
{
[super viewDidAppear:animated];
[self becomeFirstResponder];
}
-(void)viewWillDisappear:(BOOL)animated
{
[self resignFirstResponder];
[super viewWillDisappear:animated];
}
//去到呢到都係
#end

Answer 1

Here is how I do it in an app, on start :
count = COUNTDOWN_DURATION;
countdownTimer = [NSTimer scheduledTimerWithTimeInterval:1
target:self selector:#selector(countDown)
userInfo:nil repeats:YES];
this will call a countDown method every second. Do whatever you want in that countDown method but make sure to stop the NSTimer on completion (and of course to decrement counter):
if (count < 0) {
[countdownTimer invalidate];
countdownTimer = nil;
}
...
count--;