Code example for the article "Swift, Plist and Two Smoking Scripts" https://medium.com/rosberryapps/swift-plist-and-two-smoking-scripts-94bb54cbeded

swift-build-phase-scripts-1.swift

import Foundation

// Get project URL
guard let projectDirRawValue = getenv("PROJECT_DIR"),
    let projectDirectoryPath = String(utf8String: projectDirRawValue) else {
        exit(1)
}
let projectURL = URL(fileURLWithPath: projectDirectoryPath)
// Get Info.plist path
guard let productSettingsPathRawValue = getenv("PRODUCT_SETTINGS_PATH"),
    let productSettingsPath = String(utf8String: productSettingsPathRawValue) else {
        exit(1)
}

swift-build-phase-scripts-2.swift

guard let enumerator = FileManager.default.enumerator(at: projectURL, includingPropertiesForKeys: nil) else {
    exit(1)
}
var swiftFileURLs = enumerator.allObjects
    .compactMap { $0 as? URL }
    .filter { $0.pathExtension == "swift" }

swift-build-phase-scripts-3.swift

var keys: [String] = []
for url in swiftFileURLs {
    let contents = try String(contentsOf: url, encoding: .utf8)
    for (pattern, key) in patterns {
        if contents.contains(pattern) {
            keys.append(key)
        }
    }
}

swift-build-phase-scripts-4.swift

guard let productSettings = NSDictionary(contentsOfFile: productSettingsPath) else {
    exit(1)
}
for key in keys {
    guard let value = productSettings[key] as? String else {
        // Missing key
        exit(1)
    }
    if value.isEmpty {
        // Empty description
        exit(1)
    }
}