Capture

struct · iOS 16.0+ · SDK 27.1

struct Capture<Output>

A regex component that saves the matched substring, or a transformed result, for access in a regex match. Use a `Capture` component to capture one part of a regex to access separately after matching. In the example below, `regex` matches a dollar sign (`"$"`) followed by one or more digits, a period (`"."`), and then two additional digits, as long as that pattern appears at the end of the line. Because the `Capture` block wraps the digits and period, that part of the match is captured separately. let transactions = """ CREDIT 109912311421 Payroll $69.73 CREDIT 105912031123 Travel $121.54 DEBIT 107733291022 Refund $8.42 """ let regex = Regex { "$" Capture { OneOrMore(.digit) "." Repeat(.digit, count: 2) } Anchor.endOfLine } // The type of each match's output is `(Substring, Substring)`. for match in transactions.matches(of: regex) { print("Transaction amount: \(match.1)") } // Prints "Transaction amount: 69.73" // Prints "Transaction amount: 121.54" // Prints "Transaction amount: 8.42" Each `Capture` block increases the number of components in the regex's output type. In the example above, the capture type of each match is `(Substring, Substring)`. By providing a transform function to the `Capture` block, you can change the type of the captured value from `Substring` to the result of the transform. This example declares `doubleValueRegex`, which converts the captured amount to a `Double`: let doubleValueRegex = Regex { "$" Capture { OneOrMore(.digit) "." Repeat(.digit, count: 2) } transform: { Double($0)! } Anchor.endOfLine } // The type of each match's output is `(Substring, Double)`. for match in transactions.matches(of: doubleValueRegex) { if match.1 >= 100.0 { print("Large amount: \(match.1)") } } // Prints "Large amount: 121.54" Throwing an error from a `transform` closure aborts matching and propagates the error out to the caller. If you instead want to use a failable transformation, where a `nil` result participates in matching, use ``TryCapture`` instead of `Capture`.

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This type has no directly callable members in this snapshot. See the framework’s skipped declarations for unsupported APIs.

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