objective-c - Implementing decimal through (id)sender tag with Xcode

Question

I have a simple iOS/objective C question. I have searched the forum and have tried a couple different approaches but I cant seem to figure this out, I am very new to coding so I apologize for this may seem silly. I am trying to build a simple calculator with buttons made from scratch but I am stuck on the decimal portion. I am using a switch statement to input my numbers through the button (id)sender. You can see the portion I commented out, this is where I was going to take the id tagged with 10 and write some kind of statement to implement a decimal into the float value.

I also looked at a previous post which appends the decimal place. I tried to alter the code but it seems like im missing quite a few things here.

-(IBAction)decimalButton:(id)sender{
    calculatorScreen.text = [calculatorScreen.text stringByAppendingFormat:@"."]; 
}

Any help/suggestions/sample code would be very helpful, again im sorry for the newbie question, im trying my best to learn the basics.

#import "calcViewController.h"

@implementation calcViewController



-(IBAction)buttonDigitPressed:(id)sender { //ditits presed with sender tag
//    switch ([sender tag]) {
//        case 1:
//            currentNumber = 1;
//            break;
//        case 2:
//            currentNumber = 2;
//            break;
//        case 3:
//            currentNumber = 3;
//            break;
//        case 4:
//            currentNumber = 4;
//            break;
//        case 5:
//            currentNumber = 5;
//            break;
//        case 6:
//            currentNumber = 6;
//            break;
//        case 7:
//            currentNumber = 7;
//            break;
//        case 8:
//            currentNumber = 8;
//            break;
//        case 9:
//            currentNumber = 9;
//            break;
//        case 10:
//            //possibly implement decimal here 
//            break;
//    }


    currentNumber = (float)[sender tag]; //sets currentNumber to buttonPressed
    calculatorScreen.text = [NSString stringWithFormat:@"%g",currentNumber];//displays button
}


-(IBAction)buttonOperationPressed:(id)sender {
    //currentOperation is 0 by system default?

    if (currentOperation == 0) 
        result = currentNumber;

    else {
        switch (currentOperation) {
            case 1:
                result = result + currentNumber;
                break;
            case 2:
                result = result - currentNumber;
                break;
            case 3:
                result = result * currentNumber;
                break;
            case 4:
                result = result / currentNumber;
                break;
            case 5:
                currentOperation = 0;
                break;
        }
    }
    //currentNumber = 0;

    currentNumber = result; //current number equals last resulting equation
    calculatorScreen.text = [NSString stringWithFormat:@"%g",result]; //screen prints result
    if ([sender tag] == 0) result = 0;
    currentOperation = [sender tag];
}

Answer 1

The code below should update the screen correctly.

-(IBAction)buttonDigitPressed:(id)sender { //ditits presed with sender tag
    switch ([sender tag]) {
        case 1:
        case 2:
        case 3:
        case 4:
        case 5:
        case 6:
        case 7:
        case 8:
        case 9:
            calculatorScreen.text = [calculatorScreen.text stringByAppendingFormat:@"%d", [sender tag]];
            break;

        case 10:
            NSRange range = [calculatorScreen.text rangeOfString:@"."];
            if ( range.location == NSNotFound ) {
                calculatorScreen.text = [calculatorScreen.text stringByAppendingString:@"."];
            }
            break;
    }
}

To use this in calculations, use

float screenNumber = [calculatorScreen.text floatValue];