Question

I’m trying to make a pretty simple game and I’m stuck. Basically I want to make a UIImageView appear every 2 seconds. My problem is I can’t keep track of cumulative time. Right now I have this:

NSDate *date = [NSDate date];

NSTimeInterval secondsSinceNow = [date timeIntervalSinceNow];

NSLog(@"date = %@", date);
NSLog(@"secondsSinceNow = %f", secondsSinceNow);

It’s in my button function so its called when the user taps the button. It returns a decimal number always less than 1. I’ve tried it in the viewDidLoad method as well as it’s own method but neither work.

I think it would work if its in it’s own method that is check constantly, but I don’t know how to do that.

In short, I need a timer/counter that updates every second.

Answer 1

@interface className
{
NSTimer * timer;
}

@property (nonatomic, retain) NSTimer * timer;

@end


@implementation className
@synthesize timer;

...

/*factory method was corrected here. should work without warnings by copying and pasting */

-(void) applicationDidFinishLaunching : (UIApplication *) application {
timer = [NSTimer scheduledTimerWithTimeInterval: 1.0 target:self selector:@selector(targetMethod:) userInfo:nil repeats: YES];

}

//define the target method

/*method was corrected because it needed parentheses around NSTimer */

-(void) targetMethod: (NSTimer *) theTimer {
NSLog(@"Me is here at 1 minute delay");
}
..
@end

taken from here
http://www.iphonedevsdk.com/forum/iphone-sdk-development/14403-nstimer-examples.html