[iOS - swift] 문자열 파일 저장하기 (userDomainMask, documentDirectory)

긴 문자열 파일을 저장하고 싶은 경우

• keychain (x)
• userDefault (x)
• 긴 문자열을 저장하는데 적합한 FileManager를 이용하여 documentDirectory에 저장

사용 방법

• 파일이름 정의: 상수 이용

struct Constants {
    static let sampleFileName = "sampleFile"
}

• save 함수 정의 (String에 extension하여 사용하면 재활용성 상승)

    func saveFile(stringData: String, fileName: String) {
        let directory = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask)[0]
        let sampleFileName = directory.appendingPathComponent(fileName)
        do {
            try stringData.write(to: sampleFileName, atomically: true, encoding: .utf8)
        } catch let error {
            print(error.localizedDescription)
        }
    }

• load 함수 정의

    func loadFile(name: String) -> String? {
        let nsDocumentDirectory = FileManager.SearchPathDirectory.documentDirectory
        let nsUserDomainMask = FileManager.SearchPathDomainMask.userDomainMask
        let paths = NSSearchPathForDirectoriesInDomains(nsDocumentDirectory, nsUserDomainMask, true)
        if let dirPath = paths.first {
            let file = URL(fileURLWithPath: dirPath).appendingPathComponent(name)
            if let data = try? Data(contentsOf: file) {
                let dataString = String(data: data, encoding: .utf8)
                return dataString
            }
            return nil
        }
        return nil
    }

사용하는 쪽의 예시

• 저장

let piString = "3.141592653589793238462643383279502884197169399375105820974944592307816406286 208998628034825342117067982148086513282306647093844609550582231725359408128481 117450284102701938521105559644622948954930381964428810975665933446128475648233 786783165271201909145648566923460348610454326648213393607260249141273724587006 606315588174881520920962829254091715364367892590360011330530548820466521384146 951941511609433057270365759591953092186117381932611793105118548074462379962749 567351885752724891227938183011949129833673362440656643086021394946395224737190 702179860943702770539217176293176752384674818467669405132000568127145263560827 785771342757789609173637178721468440901224953430146549585371050792279689258923 542019956112129021960864034418159813629774771309960518707211349999998372978049"
saveFile(piString)

• 로드

let stringData = self.loadFile(name: Constants.sampleFile)
print(stringData)