Swift String Pad - Swift

In Swift, adding padding to a string can sometimes be a challenge. Fortunately, there are a few different approaches you can take to achieve the desired result.

In this article, we'll cover several methods for adding padding to a Swift string, including using the padding(toLength:withPad:startingAt:) method, creating a custom padding function, and using the String(format:) method to achieve padding.

Using padding(toLength:withPad:startingAt:)

The padding(toLength:withPad:startingAt:) method allows you to add padding to a string by specifying the desired length of the resulting string, the padding character to use, and the starting index for the padding. Here's an example:

let str = "Hello"
let paddedString = str.padding(toLength: 10, withPad: "-", startingAt: 0)
print(paddedString) // Output: "Hello-----"

In this example, we're padding the str variable with - characters to create a 10-character string. The startingAt parameter is optional and defaults to str.count, meaning the padding characters will be added after the end of the original string.

Creating a Custom Padding Function

Another approach to adding padding to a string in Swift is to create a custom function that takes a string, a desired length, and a padding character as arguments. Here's an example implementation:

func padString(_ value: String, toLength length: Int, withPad pad: Character) -> String {
    let paddingLength = max(0, length - value.count)
    let padding = String(repeating: pad, count: paddingLength)
    return value + padding
}

let str = "Hello"
let paddedString = padString(str, toLength: 10, withPad: "-")
print(paddedString) // Output: "Hello-----"

In this example, we're using the max function to ensure that the paddingLength value is always non-negative, and then creating a string of padding characters using the String(repeating:count:) initializer. Finally, we're concatenating the original string with the padding string to create the final padded result.

Using String(format:)

A third approach to adding padding to a Swift string is to use the String(format:) method along with the % symbol to specify the desired padding width and character. Here's an example:

let str = "Hello"
let paddedString = String(format: "%-10s", str)
print(paddedString) // Output: "Hello     "

In this example, we're using the % symbol to specify a left-aligned string of 10 characters, padded with spaces. The - symbol before the 10 indicates left alignment.

Conclusion

In conclusion, Swift provides several different approaches for adding padding to a string. Whether you prefer to use built-in methods like padding(toLength:withPad:startingAt:), create custom functions, or use String(format:) with format specifiers, there's a way to achieve the desired result.