String

string() validates text values.

Use string rules for common inputs like emails, phone numbers, IDs, IPs, and custom regex patterns.

notEmpty

Value must not be an empty string.

Parameters

message: LocalizedStringResource? – optional custom error message if empty

swift

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? – optional custom error message if whitespace is found

swift

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: ((Int) -> LocalizedStringResource)? – optional custom error message builder

swift

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: ((Int) -> LocalizedStringResource)? – optional custom error message builder

swift

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: ((Int) -> LocalizedStringResource)? – optional custom error message builder

swift

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: ((String, String) -> LocalizedStringResource)? – optional custom error message builder

swift

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? – optional custom error message if pattern does not match

swift

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? – optional custom error message if invalid

swift

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? – optional custom error message if invalid

swift

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? – optional custom error message if invalid

swift

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? – optional custom error message if invalid

swift

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? – optional custom error message if invalid

swift

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? – optional custom error message if invalid

swift

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? – optional custom error message if invalid

swift

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? – optional custom error message if invalid

swift

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? – optional custom error message if invalid

swift

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? – optional custom error message if invalid

swift

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? – optional custom error message if invalid

swift

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

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

e164phoneNumber

E.164-like phone number validation.

Parameters

message: LocalizedStringResource? – optional custom error message if invalid

swift

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

swift

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

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

endsWith

Value must end with the given suffix.

Parameters

suffix: String – required ending substring
message: ((String) -> LocalizedStringResource)? – optional custom error message builder

swift

let endsWithRule = FormCraftValidationRules()
  .string()
  .endsWith(suffix: ".com")

endsWithRule.validate(value: "example.com") // ✅ is valid
endsWithRule.validate(value: "example.org") // ❌ is not valid

includes

Value must contain the given substring.

Parameters

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

swift

let includesRule = FormCraftValidationRules()
  .string()
  .includes(substring: "@")

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

uppercase

Value must be fully uppercase.

Parameters

message: LocalizedStringResource? – optional custom error message if value is not uppercase

swift

let uppercaseRule = FormCraftValidationRules()
  .string()
  .uppercase()

uppercaseRule.validate(value: "ABC") // ✅ is valid
uppercaseRule.validate(value: "AbC") // ❌ is not valid

lowercase

Value must be fully lowercase.

Parameters

message: LocalizedStringResource? – optional custom error message if value is not lowercase

swift

let lowercaseRule = FormCraftValidationRules()
  .string()
  .lowercase()

lowercaseRule.validate(value: "abc") // ✅ is valid
lowercaseRule.validate(value: "aBc") // ❌ is not valid

String ​

notEmpty ​

trimmed ​

min ​

max ​

length ​

equals ​

regex ​

cuid ​

cuid2 ​

ulid ​

uuid ​

nanoId ​

ipv4 ​

ipv6 ​

cidrv4 ​

cidrv6 ​

isoDate ​

email ​

e164phoneNumber ​

startsWith ​

endsWith ​

includes ​

uppercase ​

lowercase ​

String

notEmpty

trimmed

min

max

length

equals

regex

cuid

cuid2

ulid

uuid

nanoId

ipv4

ipv6

cidrv4

cidrv6

isoDate

email

e164phoneNumber

startsWith

endsWith

includes

uppercase

lowercase