Question: Let's say I'm creating NSTimer in some place in the code and later, I want to add it to the mainRunLoop only if it wasn't already added before:

```
NSTimer* myTimer = [NSTimer timerWithTimeInterval:1.0f
                                                target:self
                                                selector:@selector(targetMethod:)
                                                userInfo:nil
                                                repeats:YES];

```

Another place in the code:

```
if("my myTimer wasn't added to the mainRunLoop")
{
    NSRunLoop *runLoop = [NSRunLoop mainRunLoop];
    [runLoop addTimer:myTimer forMode:NSDefaultRunLoopMode];
}

```

Is there a way to check this?

Answer: 
Try this:

```
CFRunLoopRef loopRef = [[NSRunLoop mainRunLoop] getCFRunLoop];
BOOL timerAdded = CFRunLoopContainsTimer(loopRef, (CFRunLoopTimerRef)myTimer ,kCFRunLoopDefaultMode);

```

then check `timerAdded` variable
Yes; keep a reference to it in an instance variable and check for non-`nil`:

```
@interface MyClass() {
    NSTimer *_myTimer;
}
@end

...

if (!_myTimer)
{
    _myTimer = [NSTimer timerWithTimeInterval:1.0f
                                       target:self
                                     selector:@selector(targetMethod:)
                                     userInfo:nil
                                      repeats:YES];
    NSRunLoop *runLoop = [NSRunLoop mainRunLoop];
    [runLoop addTimer:_myTimer forMode:NSDefaultRunLoopMode];
}

```