iPhone

iPhone – NSTimer Example

24 Comments

If you want to scheduled a task, NSTimer can help you. Here comes the example.

MyViewController.h

...
@interface MyViewController : UIViewController  {
	NSTimer *aTimer;
}
@property (nonatomic, retain) NSTimer *aTimer;
...

 

MyViewController.m

...
@synthesize aTimer;
...

/* Schedule a task whenever the view is load */
- (void)viewDidLoad {
	[super viewDidLoad];
	// Schedule the runScheduledTask in 5 seconds
	aTimer = [NSTimer scheduledTimerWithTimeInterval:5.0 target:self selector:@selector(runScheduledTask) userInfo:nil repeats:NO];
}

/* runScheduledTask */
- (void)runScheduledTask {
	// Do whatever u want
	...
	// Set the timer to nil as it has been fired
	aTimer = nil;
}

/* Don't forget to release the objects */
- (void)dealloc {
	[aTimer release];
	[super dealloc];
}

 

Done =)

24 thoughts on “iPhone – NSTimer Example” 

  2. #import 
#import 
 
 @interface nstimerex: NSObject
 {
 }
 -(void) try;
 
 -(void) tryc;
 
 @end
-------
#import "nstimerex.h"

@implementation nstimerex

-(void)try
{
        NSLog(@" I am in try");

        NSTimer *timer=[NSTimer  scheduledTimerWithTimeInterval:10.0 target:self selector:@selector(tryb:) userInfo:nil repeats:YES];
        [timer retain];

}

-(void)tryb:(NSTimer *)timer
{
       NSLog(@"I am in try1");
       [self tryc];
}

-(void)tryc
{
       NSLog(@"I am in try2");
 
}
@end

int main()
{
nstimerex *ob1=[[[nstimerex alloc]init]retain];
[ob1 try];

return 0;
}

    m trying to program a sample timer …the problem m facing is that it never jumps to the target method……nothing happens and the next line is executed…..can someone tell me what’s wrong with it…!!!

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    Reply

    1. what is the purpose of the NSTimer input argument?
      -(void)tryb:(NSTimer *)timer

      And there is a colon for the selector argument (tryb:).
      NSTimer *timer=[NSTimer scheduledTimerWithTimeInterval:10.0 target:self selector:@selector(tryb:) userInfo:nil repeats:YES];

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      Reply

    1. oic, i just realized i didn’t follow the Apple API. =P

      i have no idea why it does not work and seems you are not developing a iphone application. could u send me the example project?

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      Reply

  4. well actually I am definitely developing for mac os and what it refers to is for Mac as well…though I solved the problem by just removing the semicolon in selector method (as u suggested)and its working great ..sorry can’t send project details….its confidential!!

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  5. Hi thank you for this function but I have problem no action happen it’s mean not working with my code please could you check on my could is very simple 

    #import "bqtViewController.h"

#import "Home.h"

@implementation bqtViewController

@synthesize aTimer;


- (void)viewDidUnload
{
    
    [super viewDidUnload];
    aTimer = [NSTimer scheduledTimerWithTimeInterval:0.1 target:self selector:@selector(runScheduledTask) userInfo:nil repeats:NO];
    // Release any retained subviews of the main view.
    // e.g. self.myOutlet = nil;
}


-(IBAction)pushButton
{
    
    Home *second = [[Home alloc] initWithNibName:nil bundle:nil];
    
    second.modalTransitionStyle = UIModalTransitionStyleFlipHorizontal; 
    [self presentModalViewController:second animated:YES];
    
}	


- (void)runScheduledTask {
	// Do whatever u want
    Home *second = [[Home alloc] initWithNibName:nil bundle:nil];
    
    second.modalTransitionStyle = UIModalTransitionStyleFlipHorizontal; 
    [self presentModalViewController:second animated:YES];
	// Set the timer to nil as it has been fired
	aTimer = nil;
}

- (void)dealloc
{
    [aTimer 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

/*
// Implement viewDidLoad to do additional setup after loading the view, typically from a nib.
- (void)viewDidLoad
{
    [super viewDidLoad];
}
*/



- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
    
    // Return YES for supported orientations
    return (interfaceOrientation == UIInterfaceOrientationPortrait);
}

@end

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    1. you are instantiating a Home object for every 0.1 second?

      what about if u only print a log in the runScheduledTask, does it work?

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      Reply

  6. Hi thanks for quick reply I try to switch to another view like 5 sec or 1 however but still not working they are no error any idea ?

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    1. first let’s figure out if the NSTimer works or not.

      what happen if you replace the runScheduledTask as follow?

      - (void)runScheduledTask {
  // Do whatever u want
  NSLog(@"Hello World");
  // Set the timer to nil as it has been fired
  aTimer = nil;
}

      is the log printed?

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      Reply

  7. I did but still no action and the log file is empty.

    here the code for h file

    #import 

@interface bqtViewController : UIViewController {
 NSTimer *aTimer;
    
}

-(IBAction)pushButton;
@property (nonatomic, retain) NSTimer *aTimer;
@end

    —–

    Thanks Man 🙂

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    1. O, you should put the code in ViewDidLoad instead of ViewDidUnload.

      i didn’t notice that. =P

      and my previous comment was wrong, you only run the timer once because of repeats:NO.

      does it solve the problem?

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      Reply

    1. what u are doing now is setting up the aTimer in the ViewDidUnload.

      - (void)viewDidUnload
{
  [super viewDidUnload];
  aTimer = [NSTimer scheduledTimerWithTimeInterval:0.1 target:self selector:@selector(runScheduledTask) userInfo:nil repeats:NO];
  // Release any retained subviews of the main view.
  // e.g. self.myOutlet = nil;
}

       

      This code will run only when the View is UNLOADED. That’s y your timer does not run.

      You should put the code in the ViewDidLoad method instead.

      - (void)viewDidLoad
{
  [super viewDidLoad];
  aTimer = [NSTimer scheduledTimerWithTimeInterval:0.1 target:self selector:@selector(runScheduledTask) userInfo:nil repeats:NO];
  // Release any retained subviews of the main view.
  // e.g. self.myOutlet = nil;
}

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      Reply

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