NSTextField - actions within *textField - objective-c

Question

I need help using NSTextField and its inputs/outputs.
In a functioning code I have three different NSTextFields (in Cocoa + Obj-C) I know how calculate result from more integer inputs...
--- AppController.h ---
#interface AppController : NSObject {
IBOutlet NSTextField *firsTextField; // 1st Outlet
IBOutlet NSTextField *secondTextField; // 2nd Outlet
IBOutlet NSTextField *resultTextField; // 3rd Outlet
}
- (IBAction)result:(id)sender;
#end
--- AppController.m ---
#Implementation AppController
- (IBAction)result:(id)sender {
double first = [firstTextField doubleValue]; // set value 1st outlet
double second = [secondTextField doubleValue]; // set value 2nd outlet
double result = first + second; // count result
[resultTextField setDoubleValue:result]; // set value 3rd outlet
}
#end
But while I try do the same thing in only one NSTextField, I don't know how to do it... My idea is, that process should be following:
Set 1st integer (input)
*Choose math function "/, , -, +" (method/action)
Set 2nd integer (input)
Result (method/action) for calculating above mentioned inputs based on math function
But it is actually all what I am able to explain... problem is that I don't know how I can store 1st input value (before choosing math function) and how to count up result between 1st and 2nd input value.
Thank you in advance for every tip / link / reference / tutorial / etc.

Answer 1

As long as you have only one cycle, it is pretty easy. (BTW: The human math syntax (infix notation) is a little bit weird for computer programming, priority rules and brackets are needed, so some invented another algebraic syntax, the PN or reverse PN.)
When a operator is pressed, you store the operator and the first operand into a ivar. This is a state you enter and usually in GUI programming you try to prevent states. However it is, what users expect from a calculator.
First let us beautify your code with properties and generated ivars.
#interface AppController : NSObject
#property (weak, nonatomic) IBOutlet NSTextField *operandTextField;
#property (weak, nonatomic) IBOutlet NSTextField *resultTextField;
#end
Add properties for the first value and the operation:
#interface AppController : NSObject
#property (weak, nonatomic) IBOutlet NSTextField *operandTextField;
#property (weak, nonatomic) IBOutlet NSTextField *resultTextField;
#property (nonatomic) double operand;
#property (nonatomic) NSString *operator;
#end
Then you need the actions for the operations. Here is an example for one:
#interface AppController : NSObject
#property (weak, nonatomic) IBOutlet NSTextField *operandTextField;
#property (weak, nonatomic) IBOutlet NSTextField *resultTextField;
#property (nonatomic) double operand;
#property (nonatomic) NSString *operator;
- (IBAction)plus:(id)sender;
#end
The next thing you need is to add an action for "operation begin". You can connect it to the text field and make it its "enter" action.
#interface AppController : NSObject
#property (weak, nonatomic) IBOutlet NSTextField *operandTextField;
#property (weak, nonatomic) IBOutlet NSTextField *resultTextField;
#property (nonatomic) double operand;
#property (nonatomic) NSString *operator;
- (IBAction)plus:(id)sender;
- (IBAction)operate:(id)sender;
#end
Okay, done with the interface. Let's go to the implementation:
#implementation AppController
- (IBAction)plus:(id)sender
{
// Store operator
self.operator = [valueTextField doubleValue]; // Some checking?
// Store operation
self.operation = #"+"; // You can use int constant for that, but this is the easy way
}
- (IBAction)operate:(id)sender
{
// Check, whether a operation is already selected
if ([self.operation length]==0)
{
// No: Do nothing
return;
}
// Get the second operand
double operand = [valueTextField doubleValue];
// Do the calculation
double result;
if ([self.operation isEqualToString:#"+"])
{
result = self.operand + operand;
}
else if ([self.operation isEqualToString:#"-"])
{
result = self.operand - operand;
}
…
[self.resultTextField setDoubleValue:result];
self.operation = #"";
// If you do not set this, the next operand will start a new calculation with the first
// operand. Another feature would be to store the result we got and repeatedly perform
// the operation on the last result. But I would change the UI in that case.
}
#end
Typed in Safari.

Answer 2

after what I studying your code ... I'm finally got functional code ;-)
at first... here is how looks app:
and here is the code:
---------- CalcController.h -----------
#import <Foundation/Foundation.h>
#import <Cocoa/Cocoa.h>
#interface CalcController : NSObject {
IBOutlet NSTextField *textField;
}
#property (weak) IBOutlet NSTextField *operandTextField;
#property (weak) IBOutlet NSTextField *resultTextField;
#property (nonatomic) double value1;
#property (nonatomic) double value2;
#property (nonatomic) double result;
#property (nonatomic) NSString *operator;
- (IBAction)plus:(id)sender;
- (IBAction)result:(id)sender;
#end
---------- CalcController.m -----------
#import "CalcController.h"
#implementation CalcController
#synthesize operandTextField;
#synthesize resultTextField;
#synthesize value1;
#synthesize value2;
#synthesize result;
#synthesize operator;
- (IBAction)plus:(id)sender {
value1 = [textField doubleValue];
NSLog(#"operand1 = %lf", value1); // for test and see value in console
[textField setStringValue:#""]; // for clear text after 1st input done
operator = #"+";
}
- (IBAction)result:(id)sender {
value2 = [textField doubleValue];
NSLog(#"operand2 = %lf", value2); // for test and see value in console
if ([operator isEqualToString:#"+"]) {
result = value1 + value2;
NSLog(#"value1: %lf + value2: %lf = result: %lf", value1, value2, result); // for tests and see values in console
}
[resultTextField setDoubleValue:result];
operator = #"";
}
#end
I Think that working good .... now it is time to add next functions, buttons with numbers etc...
Thanks for showing the right way to do this!