enumerateSubstrings(in:options:_:)

Declaration

func enumerateSubstrings<R>(in range: R, options opts: String.EnumerationOptions = [], _ body: @escaping (String?, Range<Self.Index>, Range<Self.Index>, inout Bool) -> Void) where R : RangeExpression, R.Bound == String.Index

Parameters

• range:

  The range within the string to enumerate substrings.

• opts:

  Options specifying types of substrings and enumeration styles. If opts is omitted or empty, body is called a single time with the range of the string specified by range.

• body:

  The closure executed for each substring in the enumeration. The closure takes four arguments:

  • The enumerated substring. If substringNotRequired is included in opts, this parameter is nil for every execution of the closure.

  • The range of the enumerated substring in the string that enumerate(in:options:_:) was called on.

  • The range that includes the substring as well as any separator or filler characters that follow. For instance, for lines, enclosingRange contains the line terminators. The enclosing range for the first string enumerated also contains any characters that occur before the string. Consecutive enclosing ranges are guaranteed not to overlap, and every single character in the enumerated range is included in one and only one enclosing range.

  • An inout Boolean value that the closure can use to stop the enumeration by setting stop = true.

Discussion

Mutation of a string value while enumerating its substrings is not supported. If you need to mutate a string from within body, convert your string to an NSMutableString instance and then call the enumerateSubstrings(in:options:using:) method.