Instance Methodswift 6.0.1Swift
reserveCapacity(_:)
Reserves enough space to store the specified number of key-value pairs.
mutating func reserveCapacity(_ minimumCapacity: Int) Parameters
- minimumCapacity
The requested number of key-value pairs to store.
If you are adding a known number of key-value pairs to a dictionary, use this method to avoid multiple reallocations. This method ensures that the dictionary has unique, mutable, contiguous storage, with space allocated for at least the requested number of key-value pairs.
Calling the reserveCapacity(_:) method on a dictionary with bridged storage triggers a copy to contiguous storage even if the existing storage has room to store minimumCapacity key-value pairs.
Other members in extension
Types
struct IndexThe position of a key-value pair in a dictionary.
struct IteratorAn iterator over the members of a
Dictionary<Key, Value>.struct KeysA view of a dictionary’s keys.
struct ValuesA view of a dictionary’s values.
Typealiases
Type members
init(dictionaryLiteral: (Key, Value)...) Creates a dictionary initialized with a dictionary literal.
Instance members
var capacity: IntThe total number of key-value pairs that the dictionary can contain without allocating new storage.
var count: IntThe number of key-value pairs in the dictionary.
var customMirror: MirrorA mirror that reflects the dictionary.
var debugDescription: StringA string that represents the contents of the dictionary, suitable for debugging.
var description: StringA string that represents the contents of the dictionary.
var endIndex: Dictionary<Key, Value>.IndexThe dictionary’s “past the end” position—that is, the position one greater than the last valid subscript argument.
var isEmpty: BoolA Boolean value that indicates whether the dictionary is empty.
var keys: Dictionary<Key, Value>.KeysA collection containing just the keys of the dictionary.
var startIndex: Dictionary<Key, Value>.IndexThe position of the first element in a nonempty dictionary.
var values: Dictionary<Key, Value>.ValuesA collection containing just the values of the dictionary.
subscript(Key) -> Value? Accesses the value associated with the given key for reading and writing.
subscript(Dictionary<Key, Value>.Index) -> Dictionary<Key, Value>.Element Accesses the key-value pair at the specified position.
subscript(Key, default: @autoclosure () -> Value) -> Value Accesses the value with the given key, falling back to the given default value if the key isn’t found.
func compactMapValues<T>((Value) throws -> T?) rethrows -> Dictionary<Key, T> Returns a new dictionary containing only the key-value pairs that have non-
nilvalues as the result of transformation by the given closure.func filter((Dictionary<Key, Value>.Element) throws -> Bool) rethrows -> [Key : Value] Returns a new dictionary containing the key-value pairs of the dictionary that satisfy the given predicate.
func formIndex(after: inout Dictionary<Key, Value>.Index) func index(after: Dictionary<Key, Value>.Index) -> Dictionary<Key, Value>.Index func index(forKey: Key) -> Dictionary<Key, Value>.Index? Returns the index for the given key.
func makeIterator() -> Dictionary<Key, Value>.Iterator Returns an iterator over the dictionary’s key-value pairs.
func mapValues<T>((Value) throws -> T) rethrows -> Dictionary<Key, T> Returns a new dictionary containing the keys of this dictionary with the values transformed by the given closure.
func merge([Key : Value], uniquingKeysWith: (Value, Value) throws -> Value) rethrows Merges the given dictionary into this dictionary, using a combining closure to determine the value for any duplicate keys.
func merge<S>(S, uniquingKeysWith: (Value, Value) throws -> Value) rethrows Merges the key-value pairs in the given sequence into the dictionary, using a combining closure to determine the value for any duplicate keys.
func merging([Key : Value], uniquingKeysWith: (Value, Value) throws -> Value) rethrows -> [Key : Value] Creates a dictionary by merging the given dictionary into this dictionary, using a combining closure to determine the value for duplicate keys.
func merging<S>(S, uniquingKeysWith: (Value, Value) throws -> Value) rethrows -> [Key : Value] Creates a dictionary by merging key-value pairs in a sequence into the dictionary, using a combining closure to determine the value for duplicate keys.
func popFirst() -> Dictionary<Key, Value>.Element? Removes and returns the first key-value pair of the dictionary if the dictionary isn’t empty.
func remove(at: Dictionary<Key, Value>.Index) -> Dictionary<Key, Value>.Element Removes and returns the key-value pair at the specified index.
func removeAll(keepingCapacity: Bool) Removes all key-value pairs from the dictionary.
func removeValue(forKey: Key) -> Value? Removes the given key and its associated value from the dictionary.
func updateValue(Value, forKey: Key) -> Value? Updates the value stored in the dictionary for the given key, or adds a new key-value pair if the key does not exist.