CODEWITHSUNDEEP
objective-ciosselectornstimer
Sciguy77
Sciguy77

Reputation: 349

NSTimer causes "unrecognized selector" crash when it fires

I'm using a NSTimer to run an animation (for now just call it myMethod). However, its causing a crash.

Here's the code:

@implementation SecondViewController


// Implement viewDidLoad to do additional setup after loading the view, typically from a nib.


- (void) myMethod
{
    NSLog(@"Mark Timer Fire");

}


- (void)viewDidLoad
{ 
[super viewDidLoad];



NSLog(@"We've loaded scan");

[NSTimer scheduledTimerWithTimeInterval:2.0
                                 target:self
                               selector:@selector(myMethod:)
                               userInfo:nil
                                repeats:YES];

animationTimer = [NSTimer scheduledTimerWithTimeInterval: 1.0 target:self selector:@selector(myMethod:) userInfo:nil repeats: YES];


}

And here's the output during the crash

-[SecondViewController myMethod:]: unrecognized selector sent to instance 0x4b2ca40 2012-06-21 12:19:53.297 Lie Detector[38912:207] * Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[SecondViewController myMethod:]: unrecognized selector sent to instance 0x4b2ca40'

So what am I doing wrong here?

Upvotes: 3

Views: 5996

Answers (4)

Dr. Polar Humenn
Dr. Polar Humenn

Reputation: 397

I ran into this problem while using Swift. It may not be evident that in Swift I discovered that the target object of NSTimer must be an NSObject.

class Timer : NSObject {
   init () { super.init() }
   func schedule() {
      NSTimer.scheduledTimerWithTimeInterval(2.0,
                             target: self,
                             selector: "myMethod",
                             userInfo: nil,
                            repeats: true)
  }
  func myMethod() {
     ...
  }
}

Hope this helps somebody.

Upvotes: 5

jscs
jscs

Reputation: 64012

The timer's action method should take one argument:

- (void)myMethod: (NSTimer *)tim
{
     // Do things
}

The name of this method is myMethod:, including the colon. Your current method's name is myMethod, without the colon, but you create your timer by passing a method name that has it: selector:@selector(myMethod:).

Currently, then, the timer sends the message myMethod: to your object; your object doesn't respond to that (but would respond to myMethod) and raises an exception.

Upvotes: 2

Abhishek
Abhishek

Reputation: 2253

either you can use only 

- (void)myMethod: (id)sender
{
 // Do things
}

or you can do (remove : from both the method name)..

animationTimer = [NSTimer scheduledTimerWithTimeInterval: 1.0 target:self selector:@selector(myMethod) userInfo:nil repeats: YES];

hope this will help you

Upvotes: 4

iArezki
iArezki

Reputation: 1271

replace this

[NSTimer scheduledTimerWithTimeInterval:2.0
                             target:self
                           selector:@selector(myMethod:)
                           userInfo:nil
                            repeats:YES];

by this 

[NSTimer scheduledTimerWithTimeInterval:2.0
                             target:self
                           selector:@selector(myMethod)
                           userInfo:nil
                            repeats:YES];

Upvotes: 3

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