In previous lessons, you learned how to manage compressed datasets efficiently and handle large numerical datasets using Swift’s powerful data-handling capabilities. Building on that foundation, today's lesson will teach you how to read and process data in batches from multiple CSV files using Swift. Reading data in smaller chunks, or batches, can significantly enhance the efficiency and speed of your code when working with large datasets.

Our focus in this lesson will be on a practical scenario in which a dataset containing car information is spread across multiple files. You will learn to read, process, and analyze this data to extract meaningful insights, such as determining the car with the lowest price.

In this lesson, we will work with a set of CSV files containing car data. Here's what a typical CSV file might look like:

Each line represents a car record with the following attributes:

• Transmission: Type of transmission (e.g., Automatic, Manual)
• Price: The price of the car
• Color: The color of the car
• Year: The manufacturing year of the car
• Model: The model of the car
• Distance Traveled (km): The kilometers the car has traveled

These files are divided into multiple parts to allow batch processing, and understanding their structure is crucial as you learn to read and process them efficiently.

Now, let's delve into reading these CSV files in batches using Swift. We'll build our solution step-by-step.

First, we need to specify the filenames for our CSV files and prepare a data structure to hold the combined data.

Here, we declare an array filenames to hold the names of the CSV files and an array of Car structs to store the car data read from the files.

Now, we'll loop through each filename, read the data using Swift's file handling capabilities, and append it to our carData array.

In this code:

• We locate each file.
• We read the contents of each file into a string and separate it into lines.
• We use a loop to process each line, skipping the header.
• For each row, we parse the model and price, appending valid data to carData.

With all data combined in carData, the next step is identifying the car with the lowest price in Swift.

Here:

• We use Swift's min(by:) method to find the car with the lowest price.
• Finally, we print the model and price of the car with the lowest price.

In this lesson, you have learned how to:

• Read data in batches from multiple CSV files using Swift’s file-handling capabilities.
• Process the data efficiently with string manipulations and error handling in Swift.
• Identify insights, such as the car with the lowest price, using Swift’s powerful array methods.

These techniques prepare you to handle similar datasets efficiently using Swift. Practice these skills with exercises designed to reinforce your understanding, focusing on reactive and efficient data-handling techniques.