Xcode warning “Property access results unused - getters should not be used for side effects”

Question

I'm getting this warning when I'm calling a local routine.

My code is this:

-(void)nextLetter {
    // NSLog(@"%s", __FUNCTION__);
    currentLetter ++;
    if(currentLetter > (letters.count - 1))
    {
        currentLetter = 0;
    }
    self.fetchLetter;
}

I'm getting the warning on the self.fetchLetter statement.

That routine looks like this:

- (void)fetchLetter {
    // NSLog(@"%s", __FUNCTION__);
    NSString *wantedLetter = [[letters objectAtIndex: currentLetter] objectForKey: @"langLetter"];

    NSString *wantedUpperCase = [[letters objectAtIndex: currentLetter] objectForKey: @"upperCase"];    


.....   
}

I prefer to fix warning messages, is there a better way to write this?

Thanks!

Answer 1

The dot notation (ie self.fetchLetter ) is meant for properties, not for arbitrary methods. The self.fetchLetter is being interpreted as "get the 'fetchLetter' property of 'self'," which isn't what you intend.

Just use [self fetchLetter] instead.

Answer 2

In newer Xcode versions, even the [object method]; may trigger the warning. But sometimes we actually do need to call a property and discard the result, for example when dealing with view controllers and we need to make sure the view is actually loaded.

So we were doing:

// Ensure view is loaded and all outlets are connected.
[self view];

This now also triggers the “Property access results unused - getters should not be used for side effects” warning. The solution is to let the compiler know it's done intentionally by casting the result type to void:

(void)[self view];

Answer 3

You're declaring fetchLetter using syntax like this?

@property (retain) id fetchLetter;

That looks wrong for what you're doing. Properties are intended to be variable accessors that (in the case of getters) don't have any side effects.

You should declare fetchLetter as a method, like so:

- (void) fetchLetter;

and access it using:

[self fetchLetter]

Answer 4

I just got my problem resolved, in my case a CoreLocation Project, using both answers from Tom and Chris -

I declare:

@property (strong, nonatomic)CLLocationManager *locationManager;

And implemented like:

@synthesize locationManager = _locationManager;
....
- (void) dealloc {
         [self locationManager];
}