String

notEmpty

Value must not be an empty string.

Parameters

• message: LocalizedStringResource – error message if empty

let notEmpty = FormCraftValidationRules()
  .string()
  .notEmpty()

notEmpty.validate(value: "text") // ✅ is valid
notEmpty.validate(value: "")     // ❌ is not valid

trimmed

No leading or trailing whitespace is allowed.

Parameters

• message: LocalizedStringResource – error message if whitespace is found

let trimmed = FormCraftValidationRules()
  .string()
  .trimmed()

trimmed.validate(value: "hello")     // ✅ is valid
trimmed.validate(value: " hello ")   // ❌ is not valid

min

Minimum length requirement.

Parameters

• min: Int – minimum number of characters
• message: LocalizedStringResource – error message if shorter

let minRule = FormCraftValidationRules()
  .string()
  .min(min: 3)

minRule.validate(value: "hey") // ✅ is valid
minRule.validate(value: "hi")  // ❌ is not valid

max

Maximum length limit.

Parameters

• max: Int – maximum number of characters
• message: LocalizedStringResource – error message if longer

let maxRule = FormCraftValidationRules()
  .string()
  .max(max: 5)

maxRule.validate(value: "short")   // ✅ is valid
maxRule.validate(value: "too long") // ❌ is not valid

length

Exact length requirement.

Parameters

• length: Int – required number of characters
• message: LocalizedStringResource – error message if length does not match

let lengthRule = FormCraftValidationRules()
  .string()
  .length(length: 6)

lengthRule.validate(value: "ABC123") // ✅ is valid
lengthRule.validate(value: "ABC12")  // ❌ is not valid

equals

Value must be equal to the given string.

Parameters

• to: String – the string to compare against
• message: LocalizedStringResource – error message if values differ

let equalsRule = FormCraftValidationRules()
  .string()
  .equals(to: "secret")

equalsRule.validate(value: "secret") // ✅ is valid
equalsRule.validate(value: "SECRET") // ❌ is not valid

regex

Validation against a custom regex pattern.

Parameters

• pattern: Regex<Substring> – regex to validate against
• message: LocalizedStringResource – error message if pattern does not match

let code4Digits = FormCraftValidationRules()
  .string()
  .regex(pattern: /^[0-9]{4}$/)

code4Digits.validate(value: "1234") // ✅ is valid
code4Digits.validate(value: "12a4") // ❌ is not valid

cuid

Value must be a valid CUID.

Parameters

• message: LocalizedStringResource – error message if invalid

let cuidRule = FormCraftValidationRules()
  .string()
  .cuid()

cuidRule.validate(value: "ckjq8y3nj0001x9m5h8b9kqzg") // ✅ is valid
cuidRule.validate(value: "invalid-cuid")              // ❌ is not valid

cuid2

Value must be a valid CUID2.

Parameters

• message: LocalizedStringResource – error message if invalid

let cuid2Rule = FormCraftValidationRules()
  .string()
  .cuid2()

cuid2Rule.validate(value: "a1b2c3d4e5f6") // ✅ is valid
cuid2Rule.validate(value: "A1B2C3")       // ❌ is not valid

ulid

Value must be a valid ULID.

Parameters

• message: LocalizedStringResource – error message if invalid

let ulidRule = FormCraftValidationRules()
  .string()
  .ulid()

ulidRule.validate(value: "01ARZ3NDEKTSV4RRFFQ69G5FAV") // ✅ is valid
ulidRule.validate(value: "01ARZ3NDEKTSV4RRFFQ69G5FA!") // ❌ is not valid

uuid

Value must be a valid UUID.

Parameters

• message: LocalizedStringResource – error message if invalid

let uuidRule = FormCraftValidationRules()
  .string()
  .uuid()

uuidRule.validate(value: "123e4567-e89b-12d3-a456-426614174000") // ✅ is valid
uuidRule.validate(value: "invalid-uuid")                        // ❌ is not valid

nanoId

Value must be a valid NanoID (21 chars).

Parameters

• message: LocalizedStringResource – error message if invalid

let nanoIdRule = FormCraftValidationRules()
  .string()
  .nanoId()

nanoIdRule.validate(value: "abcde12345_fghij-67890") // ✅ is valid
nanoIdRule.validate(value: "ABC-123")                // ❌ is not valid

ipv4

IPv4 address format validation.

Parameters

• message: LocalizedStringResource – error message if invalid

let ipv4Rule = FormCraftValidationRules()
  .string()
  .ipv4()

ipv4Rule.validate(value: "192.168.0.1") // ✅ is valid
ipv4Rule.validate(value: "999.168.0.1") // ❌ is not valid

ipv6

IPv6 address format validation.

Parameters

• message: LocalizedStringResource – error message if invalid

let ipv6Rule = FormCraftValidationRules()
  .string()
  .ipv6()

ipv6Rule.validate(value: "2001:0db8:85a3:0000:0000:8a2e:0370:7334") // ✅ is valid
ipv6Rule.validate(value: "2001:::7334")                            // ❌ is not valid

cidrv4

IPv4 CIDR notation validation.

Parameters

• message: LocalizedStringResource – error message if invalid

let cidrv4Rule = FormCraftValidationRules()
  .string()
  .cidrv4()

cidrv4Rule.validate(value: "192.168.1.0/24") // ✅ is valid
cidrv4Rule.validate(value: "192.168.1.0/33") // ❌ is not valid

cidrv6

IPv6 CIDR notation validation.

Parameters

• message: LocalizedStringResource – error message if invalid

let cidrv6Rule = FormCraftValidationRules()
  .string()
  .cidrv6()

cidrv6Rule.validate(value: "2001:db8::/32")  // ✅ is valid
cidrv6Rule.validate(value: "2001:db8::/129") // ❌ is not valid

isoDate

Date string in the format YYYY-MM-DD (leap-year aware).

Parameters

• message: LocalizedStringResource – error message if invalid

let isoDateRule = FormCraftValidationRules()
  .string()
  .isoDate()

isoDateRule.validate(value: "2024-02-29") // ✅ is valid
isoDateRule.validate(value: "2023-02-29") // ❌ is not valid

email

Email format validation.

Parameters

• message: LocalizedStringResource – error message if invalid

let emailRule = FormCraftValidationRules()
  .string()
  .email()

emailRule.validate(value: "user@example.com") // ✅ is valid
emailRule.validate(value: "user@")            // ❌ is not valid

phoneNumber

E.164-like phone number validation.

Parameters

• message: LocalizedStringResource – error message if invalid

let phoneRule = FormCraftValidationRules()
  .string()
  .e164phoneNumber()

phoneRule.validate(value: "+14155552671") // ✅ is valid
phoneRule.validate(value: "141-555-2671") // ❌ is not valid

startsWith

Value must start with the given prefix.

Parameters

• prefix: String – required starting substring
• message: ((String) -> LocalizedStringResource)? – optional custom error message builder

let startsWithRule = FormCraftValidationRules()
  .string()
  .startsWith(prefix: "Hello")

startsWithRule.validate(value: "Hello World") // ✅ is valid
startsWithRule.validate(value: "World Hello") // ❌ is not valid