Question

So I’m trying to input a time in minutes automatically into my equation when (IBAction)calculate: (id)sender is triggered. Right now I have the time going in as a UITextField (IBOutlet UITextField *amountOfInt) and I would like a time in minutes to replace that automatically when calculate is pressed. When the button is pressed I don’t want the difference in time, I need to get the total time since it was initialized to go into the equation and output into IBOutlet UILabel *bOOK every time it is pressed.

My.h is:

    IBOutlet UITextField *weight;
    IBOutlet UITextField *amountOfInt;
    IBOutlet UILabel *bOOK;
    IBOutlet UILabel *numberOfDrops;    
}


-(IBAction)calculate:(id)sender;

My .m is:

-(IBAction)calculate: (id)sender {

    static int myInt = 0;
    myInt++;

    float floatbAC = (((myInt * .6) / ([weight.text floatValue] * .57)) -  (.5678 * [amountOfTime.text floatValue]); 


    NSString *stringbOOK = [[NSString alloc] initWithFormat:@"%1.2f",floatbOOK ];

    NSString *string = [NSString stringWithFormat:@"%d", myInt];

    [numberOfDrops setText:string];

    bOOK.text = stringbOOK;

    [stringbOOK release];

Answer 1

Not sure you what you are referring to when you say it is initialised, but you can create a NSDate object when your ‘it’ gets initialised, like

initialiseDate = [[NSDate alloc] init];

and then when you button is pressed use the timeIntervalSinceDate method

NSTimeInterval differenceInSeconds = [[NSDate date] timeIntervalSinceDate:initialiseDate];

This might give you a negative result, can’t remember which is subtracted from which, you will just have to negate the result or swap the dates around