iOS AES/CBC/PKCS7Padd128bit算法解密字符串问题

import CommonCrypto

func decryptAES(cipherText: Data, key: Data, iv: Data) -> String? {
    let bufferSize = cipherText.count + kCCBlockSizeAES128
    var buffer = [UInt8](repeating: 0, count: bufferSize)
    var numBytesDecrypted: size_t = 0
    
    let cryptStatus = key.withUnsafeBytes { keyBytes in
        iv.withUnsafeBytes { ivBytes in
            cipherText.withUnsafeBytes { cipherTextBytes in
                CCCrypt(
                    CCOperation(kCCDecrypt),
                    CCAlgorithm(kCCAlgorithmAES),
                    CCOptions(kCCOptionPKCS7Padding),
                    keyBytes.baseAddress,
                    key.count,
                    ivBytes.baseAddress,
                    cipherTextBytes.baseAddress,
                    cipherText.count,
                    &buffer,
                    bufferSize,
                    &numBytesDecrypted
                )
            }
        }
    }
    
    if cryptStatus == kCCSuccess {
        let decryptedData = Data(bytes: buffer, count: numBytesDecrypted)
        return String(data: decryptedData, encoding: .utf8)
    } else {
        return nil
    }
}

let cipherText = "encrypted string"
let key = "128-bit key"
let iv = "16-byte IV"

if let decryptedString = decryptAES(cipherText: Data(base64Encoded: cipherText)!, key: Data(key.utf8), iv: Data(iv.utf8)) {
    print("Decrypted string: \(decryptedString)")
} else {
    print("Decryption failed")
}