problem with NSTimer

[swestland]

Hi

I am writing an Iphone game. It's going well but I am having problems with the game loop. I am trying to use NSTimer to invoke the game loop so many times per second.

I invoke the NSTimer like this in my viewController.m

-(IBAction) createStoryid)sender {

NSLog(@"abpout to make timer");

timer = [NSTimer scheduledTimerWithTimeInterval:1.0 target:self selector:@selector(gameloop) userinfo:nil repeats:YES];

}

In viewController.h I have declared the timer thus:
@interface FieldButtonFunViewController : UIViewController {
IBOutlet UIButton *generateStory;
NSMutableArray *_them;
NSTimer *timer;
}

I have a gameloop that looks like this:

-(void) gameloop {
NSLog(@"in gameloop");
// my other code here
}

and declare gameloop in the .h file thus:

- (void) gameloop;

When I build this I get a warning

/Users/steve/Documents/FieldButtonFun/Classes/FieldButtonFunViewController.m:80: warning: 'NSTimer' may not respond to '+scheduledTimerWithTimeInterval:target:selector:u serinfo:repeats:'

I have been trying to fix it for about 4 hours. No luck. When I run the program things work until the timer is fired then it crashes.

The following appears in the console:

2010-04-02 16:47:22.804 FieldButtonFun[6129:207] *** +[NSTimer scheduledTimerWithTimeInterval:target:selector:use rinfo:]: unrecognized selector sent to class 0x1c844a0
2010-04-02 16:47:22.805 FieldButtonFun[6129:207] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '*** +[NSTimer scheduledTimerWithTimeInterval:target:selector:use rinfo:]: unrecognized selector sent to class 0x1c844a0'
2010-04-02 16:47:22.806 FieldButtonFun[6129:207] Stack: (
29295707,
2467112201,

Any ideas ... please.

Best
Steve

[ZunePod]

I had this one yesterday, I can't remember what I did, but it's something to do with the selector field.

[swestland]

Originally Posted by ZunePod

I had this one yesterday, I can't remember what I did, but it's something to do with the selector field.

Yes, the info in the console would suggest that the selector is not working properly..... but how to fix it?
S

[Kalimba]

The method that you're referencing does not exist in the NSTimer class. Check the reference manual here: Mac Dev Center: NSTimer Class Reference and see if you can figure out what you're doing wrong.

[ZunePod]

It might be the space that you have

- (void) gameloop

between the ) and the g.

[swestland]

Thanks Kalimba

I can see now that I should declare the method I want to be called as

- (void) gameloopNSTimer*)timer;

because the timer gets passed to the game loop as an argument.

But I still can't get it to work.

Steve

[swestland]

Think I have fixed it.

In addition to making my gameloop take an argument (the timer) I also realised I had mis-spelled userinfo - it should be userInfo thus

timer = [NSTimer scheduledTimerWithTimeInterval: (1.0f / 30.0f) target: self selector:@selector(gameloop userInfo:self repeats:YES];

It now builds without warning. Thanks!!!

I really appreciate the help.
Steve

[ZunePod]

Originally Posted by swestland

Think I have fixed it.

In addition to making my gameloop take an argument (the timer) I also realised I had mis-spelled userinfo - it should be userInfo thus

timer = [NSTimer scheduledTimerWithTimeInterval: (1.0f / 30.0f) target: self selector:@selector(gameloop userInfo:self repeats:YES];

It now builds without warning. Thanks!!!

I really appreciate the help.
Steve

BTW, you don't have to have

- (void)gameloop;

in your .h and the method doesn't need to have the NSTimer thing in there.

[Kalimba]

Originally Posted by swestland

Thanks Kalimba

I can see now that I should declare the method I want to be called as

- (void) gameloopNSTimer*)timer;

because the timer gets passed to the game loop as an argument.

But I still can't get it to work.

Steve

Re-read the warning you get when you build, and examine the error you get when you crash.

Originally Posted by swestland

When I build this I get a warning

/Users/steve/Documents/FieldButtonFun/Classes/FieldButtonFunViewController.m:80: warning: 'NSTimer' may not respond to '+scheduledTimerWithTimeInterval:target:selector:u serinfo:repeats:'

Originally Posted by swestland

2010-04-02 16:47:22.804 FieldButtonFun[6129:207] *** +[NSTimer scheduledTimerWithTimeInterval:target:selector:use rinfo:]: unrecognized selector sent to class 0x1c844a0
2010-04-02 16:47:22.805 FieldButtonFun[6129:207] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '*** +[NSTimer scheduledTimerWithTimeInterval:target:selector:use rinfo:]: unrecognized selector sent to class 0x1c844a0'

These messages essentially indicate what the problem is. The compiler is saying that your code is trying to do something specific with NSTimer class that, according to its knowledge of the class, does not exist in the class. Later on, when you invoke that method (that the compiler warned you did not exist), the app crashes because it does not recognize the method as you've typed it in your code.

So, re-read the NSTimer docs for the method that you think you're calling, and look closely at your code. Keep in mind that C/Obj-C is a case-sensitive language.

EDIT: I guess it took me a while to type this reply... Glad you figured it out.