IF Statement Seems To Work Fine On Simulator, But Not On Device!

Question

Hi Guys,

Ok, the problem is that when my app runs on the simulator it seems to work fine. On the device, however it does not update all the labels. I think the error is somewhere here:

- (IBAction)buttonclick1 {  

     self.startDate = [NSDate date];  
     double value = [self Level];  
     double value2 = [self Level2];  


if ((value2 - value) >= 3.0) {

 ifWork.text = @"DONE!";
 ifWork.textColor = [UIColor yellowColor];

 float noSeconds = (float) [self.startDate timeIntervalSinceNow]; 
  }
}

I am new to this game. What I am looking for, is when the button is pressed, it times how long it takes for an event to happen. I then would like to use this time in calculations.

I know the IF statement is correct as it works on the simulator. However on the device, when value and value2 differ by 3 and then the button is pressed, nothing happens (the label ifWork doesn't change!).

Any help would be much appreciated,

Stu

Answer 1

Did you run the code in the debugger to see what happens? Maybe if the values depend on anything like CPU or network performance you may experience notable differences between the simulator and the actual device, so you cannot be sure that what works on the simulator works on the device.

Answer 2

There could be a few reasons.

• Level1 or Level2 results could be different on device (using uninitialized memory which is different on device
• value2 - value1 could be very close to 3.0 but just less than (doubles are often a little imprecise)
• ifWork could be improperly set on the device (i.e. nil) so nothing happens.

The best solution is to debug on the device (step over this code line by line) and check if any of these things are true.