Question

I am trying to set up a running loop, and to do so I’ve the following code:

[[NSRunLoop currentRunLoop] addTimer:a forMode:NSEventTrackingRunLoopMode];

However I get an error saying “Use of undeclared identifier ‘a'”. I have both of these methods declared in my header and main file:

//AppController.h
#import <Foundation/Foundation.h>
@interface AppController : NSObject
- (IBAction) startLoop: (id)sender;
- (void) a: (id)sender;
@end

//AppController.m
#import "AppController.h"
@implementation AppController
-(IBAction) startLoop: (id) sender {
    [[NSRunLoop currentRunLoop] addTimer:a forMode:NSEventTrackingRunLoopMode];
}
-(void) a: (id) sender {
    //Code here 
}
@end

I’m new to Objective-C so I apologise in advance for any silly mistakes, thanks.

Answer 1

The addTimer:: method wants its first parameter to be a NSTimer object. The only thing visible in your code that’s (almost) called a is not only not a NSTimer, but not an object at all. It’s a method. Do you have a timer created somewhere that you intended to use?

(Technically, the method’s name is a: rather than a.)