bnb

Formatting Swift Log Entries for Readability

Yesterday, we explored how to filter log messages in Xcode. Today we're going to be working on making the messages more readable.

Standard Formatters

Logging uses interpolation, but there are additional arguments that can be provided. For example, Booleans can be formatted as .answer.

Logger.spicy.trace("Was this salsa spicy? \(isSpicy, format: .answer)")
// Was this salsa spicy? YES

Of course, different data types have different formats available. Int32 has the most available, including .byteCount and .ipv4Address.

Logger.spicy.trace("Color: \(color, format: .hex(includePrefix: true, uppercase: true, minDigits: 6))")
Logger.spicy.trace("Byte count: \(byteCount, format: .byteCount)")
Logger.spicy.trace("IP Address: \(ipAddress, format: .ipv4Address)")

// Color: 0x00FF00
// Byte count: 61.8 kB
// IP Address: 146.74.186.126

Enable logging via CustomStringConvertable

For custom types, implementing the CustomStringConvertable protocol will allow interpolation to work in logging messages.

struct Sauce: CustomStringConvertible {
    let name: String
    let manufacturer: String

    // MARK: - CustomStringConvertable

    var description: String {
        "\(name) by \(manufacturer)"
    }
}

Logger.spicy.trace("Sauce: \(sauce)")
// Sauce: Awesome Sauce by Acme Inc

Coming up next

Tomorrow we'll be focused on protecting privacy of personally identifiable information (PII).

Recent posts