Dictionary

extension Dictionary

  • Creates a new dictionary whose keys are the groupings returned by the given closure and whose values are arrays of the elements that returned each key.

    // [Int64: [Player]]
let cursor = try Player.fetchCursor(db)
let dictionary = try Dictionary(grouping: cursor, by: { $0.teamID })

    Declaration

    Swift

    public init<C: Cursor>(grouping cursor: C, by keyForValue: (C.Element) throws -> Key)
throws where Value == [C.Element]

    Parameters

    cursor

    A cursor of values to group into a dictionary.
    keyForValue

    A closure that returns a key for each element in the cursor.
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  • Creates a new dictionary whose keys are the groupings returned by the given closure and whose values are arrays of the elements that returned each key.

    // [Int64: [Player]]
let cursor = try Player.fetchCursor(db)
let dictionary = try Dictionary(
    minimumCapacity: 100,
    grouping: cursor,
    by: { $0.teamID })

    Declaration

    Swift

    public init<C: Cursor>(minimumCapacity: Int, grouping cursor: C, by keyForValue: (C.Element) throws -> Key)
throws where Value == [C.Element]

    Parameters

    minimumCapacity

    The minimum number of key-value pairs that the newly created dictionary should be able to store without reallocating its storage buffer.
    cursor

    A cursor of values to group into a dictionary.
    keyForValue

    A closure that returns a key for each element in the cursor.
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  • Creates a new dictionary from the key-value pairs in the given cursor.

    You use this initializer to create a dictionary when you have a cursor of key-value tuples with unique keys. Passing a cursor with duplicate keys to this initializer results in a fatal error.

    // [Int64: Player]
let cursor = try Player.fetchCursor(db).map { ($0.id, $0) }
let playerByID = try Dictionary(uniqueKeysWithValues: cursor)

    Precondition

    The cursor must not have duplicate keys.

    Declaration

    Swift

    public init<C: Cursor>(uniqueKeysWithValues keysAndValues: C)
throws where C.Element == (Key, Value)

    Parameters

    keysAndValues

    A cursor of key-value pairs to use for the new dictionary. Every key in keysAndValues must be unique.
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  • Creates a new dictionary from the key-value pairs in the given cursor.

    You use this initializer to create a dictionary when you have a cursor of key-value tuples with unique keys. Passing a cursor with duplicate keys to this initializer results in a fatal error.

    // [Int64: Player]
let cursor = try Player.fetchCursor(db).map { ($0.id, $0) }
let playerByID = try Dictionary(
    minimumCapacity: 100,
    uniqueKeysWithValues: cursor)

    Precondition

    The cursor must not have duplicate keys.

    Declaration

    Swift

    public init<C: Cursor>(minimumCapacity: Int, uniqueKeysWithValues keysAndValues: C)
throws where C.Element == (Key, Value)

    Parameters

    minimumCapacity

    The minimum number of key-value pairs that the newly created dictionary should be able to store without reallocating its storage buffer.
    keysAndValues

    A cursor of key-value pairs to use for the new dictionary. Every key in keysAndValues must be unique.
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