EMI Calculator || iOS Swift | XCode | AdMob

Introduction

The EMI Calculator is a simple and essential financial tool that helps users calculate the Equated Monthly Installment (EMI) for a loan. It's a crucial step in the loan application process, and with the rise of digital lending, it's more important than ever to have a reliable and easy-to-use EMI Calculator.

In this tutorial, we'll create a complete EMI Calculator app using iOS, Swift, Xcode, and AdMob. We'll cover the following topics:

1. Creating the EMI Calculator UI
2. Implementing the EMI Calculation Logic
3. Handling User Input and Validation
4. Displaying Results and Error Messages
5. Integrating AdMob for Monetization

By the end of this tutorial, you'll have a fully functional EMI Calculator app that's ready to be published on the App Store.

Step 1: Creating the EMI Calculator UI

1. Open Xcode and create a new Single View App project.
2. Choose the "iOS" template and select "Swift" as the programming language.
3. Name your project "EMICalculator" and click "Next".

4. Set up the project structure as desired and click "Create".

5. Open the Main.storyboard file and drag a UITextView to the top of the screen. This will be our main display area.
6. Below the UITextView, drag a UIStackView to contain the input fields.

7. Add the following UI elements to the UIStackView:

   • UITextField for Loan Amount
   • UITextField for Interest Rate
   • UITextField for Tenor (in years)
   • UIButton to trigger the EMI calculation
8. Set the auto-layout constraints for each element to ensure proper spacing and alignment.

Step 2: Implementing the EMI Calculation Logic

1. Open the ViewController.swift file and add the following code:

   
   import UIKit

class ViewController: UIViewController { // UI Elements @IBOutlet weak var loanAmountTextField: UITextField! @IBOutlet weak var interestRateTextField: UITextField! @IBOutlet weak var tenorTextField: UITextField! @IBOutlet weak var resultTextView: UITextView! @IBOutlet weak var calculateButton: UIButton!

// EMI Calculation Variables
var loanAmount: Double = 0.0
var interestRate: Double = 0.0
var tenor: Int = 0

// EMI Calculation Function
func calculateEMI() {
    // Calculate EMI using the formula: EMI = (P * r * (1 + r)^n) / ((1 + r)^(n-1))
    let emi = (loanAmount * interestRate * pow(1 + interestRate, Double(tenor))) / pow(1 + interestRate, Double(tenor) - 1)
    resultTextView.text = "EMI: ₹(String(format: "%.2f", emi))"
}

}

2. In the `viewDidLoad()` method, set the `loanAmount`, `interestRate`, and `tenor` variables to default values or user input.

**Step 3: Handling User Input and Validation**

1. Add the following code to the `calculateButton`'s `Touch Up Inside` event handler:
```swift
@IBAction func calculateButtonTapped(_ sender: UIButton) {
    // Validate user input
    guard let loanAmountText = loanAmountTextField.text,
          let interestRateText = interestRateTextField.text,
          let tenorText = tenorTextField.text else {
        resultTextView.text = "Invalid input. Please enter values for Loan Amount, Interest Rate, and Tenor."
        return
    }

    // Convert user input to Double
    loanAmount = Double(loanAmountText)!
    interestRate = Double(interestRateText)! / 100 // Convert interest rate to decimal
    tenor = Int(tenorText)!

    // Calculate EMI
    calculateEMI()
}

1. Add the necessary validation logic to ensure the user enters valid input for each field.

Step 4: Displaying Results and Error Messages

1. In the calculateEMI() function, update the resultTextView with the calculated EMI value.
2. In the calculateButtonTapped() method, display an error message if the user input is invalid.

Step 5: Integrating AdMob for Monetization

1. Create an AdMob account and follow the instructions to set up your app for AdMob.
2. In the ViewController.swift file, add the following code to integrate AdMob:

   
   import Google-Mobile-Ads

class ViewController: UIViewController { //...

// AdMob Banner
let adView = GADBannerView(adSize: kGADAdSizeBanner)

override func viewDidLoad() {
    super.viewDidLoad()
    // Load AdMob banner
    adView.adUnitID = "YOUR_AD_UNIT_ID"
    adView.rootViewController = self
    adView.load(GADRequest())
}

}

3. Place the AdMob banner below the `UIStackView` in the `Main.storyboard` file.

**Conclusion**

Congratulations! You've created a fully functional EMI Calculator app with AdMob integration. Test your app on a simulator or physical device to ensure it works as expected. With this tutorial, you've learned how to create a simple yet powerful financial tool using iOS, Swift, Xcode, and AdMob. Happy coding!