Question

I have an IBAction instance method that is connected to a slider, and displays the slider value in a Text Field that has the name datacellR1. A copy of the code is below, followed by a question. Both methods are in the @implementation section of the View2Controller.m file.

- (IBAction)slider1Change:(id)sender 
{

    float pctVal1 = [slider1 floatValue];  // this works
    [datacellR1 setFloatValue:pctVal1];         

   [View2Controller CalculateUpdatedTotal ]; // This method needs to work with the datacellR1 contents, but I can’t access it.


}



-(void)CalculateUpdatedTotal  
{  

    // -------- do some work with datacellR1 ----
    // This function fails with an error

    float newValue = [datacellR1 floatValue];

    //some other code goes here   

}

The error in slider1Change is that CalculateUpdatedTotal method is not found. If I change CalculateUpdatedTotal from an instance method to a class method, the error is that the Instance variable datacellR1 accessed in a class method.

Any suggestions on how I can make this work?

Answer 1

CalculateUpdatedTotal, as written, is also an instance method. Therefore, to invoke it, you should pass the message to self, not the class (View2Controller):

[self CalculateUpdatedTotal];

By the way, it’s conventional to begin method names in Objective-C with a lower-case letter.