端端舝

Yuichi Yoshida
Chief engineer, DENSO IT Laboratory, Inc.
@sonson_twit
? 2014 DENSO IT Laboratory, Inc., All rights reserved. Redistribution or public display not permitted without written permission from DENSO IT Laboratory, Inc.
Value type programming及�手仄凶中
Programming Swift 2 (& LLDB) 扑件禾斥它丞
foldr毛午卞井仁厒仁允月

赻撩畿賡
2tch及笢及�
? iOS疑五匹允
? 2tch(ㄡ切扎氏友月申亙奈失)
? iOS SDK Hacks卅升
? 旃噶?嶱逃
? 戊件疋亙奈正申斥亦件
? 辻迮悝�
? 賒砉𨈘坰扔奈申旦午井
? �砃仃扔奈申旦支甩奈玉它尼失午井

reddift
Swift Reddit API Wrapper
? 1�|�眕奻及失丟伉市及SNS
? API丐曰
? Objective-C及API Wrapper反丐曰
? OAuth2卞�𡛟仄化卅中
? Swift元扎卅中
? 方仄ㄛ中勻切斤ㄛ𧘇庤ㄚ辭�互化日釬月井ㄐ
? MIT License
https://github.com/sonsongithub/reddift

款棗梭餃娶毛厒仁仄凶中

晨硃莽域梗梭梭卞井少木笢

foldr午foldl (�心煋心)
? Haskell及詢蕆憝杅及笢卞foldl, foldr午中丹手及互丐月
? 謎仁妏歹木月日仄中
x + a0
2
+ a1
2
+ a2
2
foldl
foldr x + a2
2
+ a1
2
+ a0
2

妏中源‵凶午尹壬欄�
〞 Haskell?
rev :: [a] -> [a]
rev = foldl (acc x -> x (: (acc-1)) []
〞 Swift?
func rev<T>(array:[T]) -> [T] {
return array.reduce([]) { (acc:[T], x:T) -> [T] in
[x] + acc
}
}

foldl毛Swift匹灍蚾仄化心方丹
foldl = reduce
皺賸

foldr毛Swift匹灍蚾仄化心方丹
foldr = reverse().reduce
皺賸?????ˋ

綈中
extension CollectionType {
func foldr_reduce<T>(accm:T, f: (T, Self.Generator.Element) -> T) -> T {
return self.reverse().reduce(accm) { f($0, $1) }
}
func foldl_reduce<T>(accm:T, @noescape f: (T, Self.Generator.Element) -> T) -> T {
return self.reduce(accm) { f($0, $1) }
}
}

燴蚕反ˋ
? 詢蕆憝杅匹綃中互衄月ˋ
? 婬䔝ㄛfor, forEach, reduce＃.
? @noescape
? 斛猁卅中及卞黱隙平乓皿民乓允月及互綈中ˋ
? 蕉尹卞仁中仃升卅丑
? reverse卞睡井�觳互丐月
? 公及引引↙厒中
? reverse允月↙綈中
? 墅仄中???

灍蚾 - 婬䔝
// recursive
var g = self.generate()
func next() -> T {
return g.next().map {x in f(x, next())} ?? accm
}
return next()
Haskell反婬䔝互霛今木化月及卞????
允什卞旦正永弁毛妘中勾少允及匹妏尹卅中

灍蚾 - for
// recursive
var result = accm
for temp in self.reverse() {
result = f(temp, result)
}
return result

灍蚾 - 陔統forEach
// forEach
var result = accm
self.reverse().forEach { (t) -> () in
result = f(t, result)
}
return result

reverse互墅仄中
? @norio_nomura今氏井日伎〝失玉田奶旦
? Swift及戊奈玉毛沷戶化中月午ㄛ伎〝瓚隴

癶籵及reverse勻弔中
extension SequenceType {
/// Return an `Array` containing the elements of `self` in reverse
/// order.
///
/// Complexity: O(N), where N is the length of `self`.
@warn_unused_result
public func reverse() -> [Self.Generator.Element]
}

逃�ㄐO(1)午井𤩸中化月
extension CollectionType where Index : BidirectionalIndexType {
/// Return the elements of `self` in reverse order.
///
/// - Complexity: O(1)
@warn_unused_result
public func reverse() -> ReverseCollection<Self>
}
extension CollectionType where Index : RandomAccessIndexType {
/// Return the elements of `self` in reverse order.
///
/// - Complexity: O(1)
@warn_unused_result
public func reverse() -> ReverseRandomAccessCollection<Self>
}

ReverseCollection
/// A Collection that presents the elements of its `Base` collection
/// in reverse order.
///
/// - Note: This type is the result of `x.reverse()` where `x` is a
/// collection having bidirectional indices.
///
/// The `reverse()` method is always lazy when applied to a collection
/// with bidirectional indices, but does not implicitly confer
/// laziness on algorithms applied to its result. In other words, for
/// ordinary collections `c` having bidirectional indices:
///
/// * `c.reverse()` does not create new storage
/// * `c.reverse().map(f)` maps eagerly and returns a new array
/// * `c.lazy.reverse().map(f)` maps lazily and returns a `LazyMapCollection`
///
/// - See also: `ReverseRandomAccessCollection`

ReverseRandomAccessCollection
/// A Collection that presents the elements of its `Base` collection
/// in reverse order.
///
/// - Note: This type is the result of `x.reverse()` where `x` is a
/// collection having random access indices.
/// - See also: `ReverseCollection`

仇及倰卞分仃extension毛灍蚾仄化心月
extension CollectionType where Index : RandomAccessIndexType {
func foldr_loop2<T>(accm:T, @noescape f: (Self.Generator.Element, T) -> T) -> T {
var result = accm
for temp in self.reverse() {
result = f(temp, result)
}
return result
}
func foldr_reduce2<T>(accm:T, @noescape f: (T, Self.Generator.Element) -> T) -> T {
return self.reverse().reduce(accm) { f($0, $1) }
}
func foldr_forEach2<T>(accm:T, @noescape f: (Self.Generator.Element, T) -> T) -> T {
var result = accm
self.reverse().forEach { (t) -> () in
result = f(t, result)
}
return result
}
}

矛件民穴奈弁氾旦玄
? https://github.com/sonsongithub/testFoldr

Value type programming反升仇引匹ˋ
? ListViewController
? 仇仇匹戊奈伙田永弁匹伉旦玄毛丹仃午月
? DetailViewController
? ListViewCon.井日伉旦玄及猁匼夫午勾毛忳仃龰月
? ��桶尨
? �摩

Pros. and cons.
? Value type.
? 痜癹午砢賃互隴復
? 厒中????ˋ
? 禾奶件正卞騻木五勻化月午勾日中
? 戊奈玉互歹井曰支允中ˋ午反佷尹卅中ㄝ
? Reference type.
? C倰左奈伙玉正奶皿卞反歹井曰支允中
? 痜癹午砢賃互戶切扎仁切扎
? 凶引卞犯奈正互戶切扎仁切扎卞卅月

犯件末奈失奶氾奴奈仿示仿玄伉匹反﹜
?????????旃噶氪ㄛ巨件斥瓦失毛羯揋躁摩笢匹允﹝
鶸庤及丐月源反仇切日﹝https://www.d-itlab.co.jp/recruit/
賒砉�I燴?辻迮悝�?陓瘍�I燴?赻�晟惤�I燴卅升

端端舝

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