UISegmentedControl - basic math, division, changing a value of an integer.

[Wes]

Hello kind SDK Masters,

I'm writing a small application which takes a number from a textfield, divides it by 18 or 27, and prints the result in a label. I would like to use segmented control to change that second value to 18 when selectedSegmentIndex == 0, and 27 when selectedSegmentIndex == 1. Could anyone tell me how to do that? Thank you in advance.

Here's the code I'd like to transform:

- (IBAction)calc {
float a = ([textField.text floatValue]);
float b = a/18;
float c = a/27;
label.text = [[NSString alloc] initWithFormat:@"%f", b];
label.text = [[NSString alloc] initWithFormat:@"%f", c];
}

[George0107]

Look up UISegmentedControl, actually here:

Herel

There's a property that returns the selected segment..

So you would check which segment is selected, (either 18, or 27)

then divide accordingly.

[That Don Guy]

Unless I'm missing something, how about:

- (IBAction)calc {
float a = ([textField.text floatValue]);
float b = a / (mySegmentedControl.segmentedSegmentIndex * 9.0 + 18.0);
label.text = [[NSString alloc] initWithFormat:@"%f", b];
}

where mySegmentedControl is the name of your UISegmentedControl variable?

(If you need information on how to add the segmented control and attach it to the code, it should be a fairly simple case of adding to the .h file:

IBOutlet UISegmentedControl *mySegmentedControl;

then add the segmented control in Interface Builder and attach a referencing outlet from the control to mySegmentedControl. Am I missing anything, given that all he really needs is the selected segment number?)

-- Don

[George0107]

Why * 9 and + 18??

But what you have is pretty much what he will need, except the part that I mentioned above ^.

I would of done a switch:

float a = [[textField text] floatValue];
int index = [UISegmentedControl selectedSegmentIndex];
switch(index) {
case 0: //18
[label setText:[NSString stringWithFormat:@"%@", (a / 18)]; //is label mutable? 
break;
case 1: //27
[label setText:[NSString stringWithFormat:@"%@", (a / 27)];
break;
}

[Wes]

Originally Posted by George0107

Why * 9 and + 18??

But what you have is pretty much what he will need, except the part that I mentioned above ^.

I would of done a switch:

float a = [[textField text] floatValue];
int index = [UISegmentedControl selectedSegmentIndex];
switch(index) {
case 0: //18
[label setText:[NSString stringWithFormat:@"%@", (a / 18)]; //is label mutable? 
break;
case 1: //27
[label setText:[NSString stringWithFormat:@"%@", (a / 27)];
break;
}

All hail, thank you so much George, that will work.

I was trying, badly of course, to pull it off like this:

// .h file

@interface Untitled : UIViewController {
	IBOutlet UISegmentedControl *choose;
	IBOutlet UITextField *textField;
	IBOutlet UILabel *label;
}

- (IBAction)calc;
- (IBAction)change;

// .m

-(IBAction)calc {
   float a = ([textField.text floatValue]);
   float b = a/y;
   label.text = [[NSString alloc] initWithFormat:@"%f", b];

-(IBAction)change { 
   switch (choose.selectedSegmentIndex) {
      case 0:
         y = 18;
	 break;
      case 1:
          y = 27;
          break;
      default:
	  break;
     }
}

That's not gone well, has it...

[That Don Guy]

Originally Posted by George0107

Why * 9 and + 18??

If selectedSegmentIndex = 0, the divisor is 0 * 9 + 18 = 18.
If selectedSegmentIndex = 1, the divisor is 1 * 9 + 18 = 27.

-- Don

[Wes]

Originally Posted by George0107

Why * 9 and + 18??

But what you have is pretty much what he will need, except the part that I mentioned above ^.

I would of done a switch:

float a = [[textField text] floatValue];
int index = [UISegmentedControl selectedSegmentIndex];
switch(index) {
case 0: //18
[label setText:[NSString stringWithFormat:@"%@", (a / 18)];
break;
case 1: //27
[label setText:[NSString stringWithFormat:@"%@", (a / 27)];
break;
}

I'm getting the following warnings:

int index = [UISegmentedControl selectedSegmentIndex]; 
/* 
1. 'UISegmentedControl' may not respond to '+selectedSegmentIndex'
(Messages without a matching method signature will be assumed to return 'id' and accept '...' as arguments.)
2. Initialization makes integer from pointer without a cast 
*/

And when I try to calculate, the application gets terminated for some reason.

[Wes]

Originally Posted by That Don Guy

If selectedSegmentIndex = 0, the divisor is 0 * 9 + 18 = 18.
If selectedSegmentIndex = 1, the divisor is 1 * 9 + 18 = 27.

-- Don

Problem solved, That Don God Thanks.

[That Don Guy]

Originally Posted by George0107

I would of done a switch:

float a = [[textField text] floatValue];
int index = [UISegmentedControl selectedSegmentIndex];
switch(index) {
case 0: //18
[label setText:[NSString stringWithFormat:@"%@", (a / 18)]; //is label mutable? 
break;
case 1: //27
[label setText:[NSString stringWithFormat:@"%@", (a / 27)];
break;
}

Originally Posted by Wes

I'm getting the following warnings:

int index = [UISegmentedControl selectedSegmentIndex]; 
/* 
1. 'UISegmentedControl' may not respond to '+selectedSegmentIndex'
(Messages without a matching method signature will be assumed to return 'id' and accept '...' as arguments.)
2. Initialization makes integer from pointer without a cast 
*/

And when I try to calculate, the application gets terminated for some reason.

There are two problems in the code.

First, in:
int index = [UISegmentedControl selectedSegmentIndex];
change "UISegmentedControl" to the actual name of your segmented control.

Second, in the two stringWithFormat calls, the format string includes %@, which is for a string, and it is expecting a string (actually, a pointer to an NSString) as a parameter, but the code has an int as the parameter. To include an int in a format string, use %i (or %qi for a "long long"), not %@.

-- Don