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What’s new in Swift?
@Kaz_Homma (Kazutaka Homma)
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@Kaz_Homma (本間 和尊)
iOS Engineer at Mercari JP
Joined on July, 2019
Github: @Kazutaka333
Twitter: @Kaz_Homma
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1. Multiple trailing closures
複数クロージャーでもカッコを省略して引数に書ける！
2. Increased availability of implicit self in closures
selfを書く回数が減る！
3. Synthesized Comparable conformance for enum types
enumにComparableプロトコルが使いやすくなった！
4. Enum cases as protocol witnesses
Enum caseでstatic var・static funcを満たすことができる！
5. KeyPath expressions as function
keyPathをクロージャーの代わりに渡せる！
Agenda
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Multiple trailing closures SE-0279
// Trailing Closure なし
UIView.animate(withDuration: 0.1, animations: {
self.view.backgroundColor = .red
})
// Trailing Closure あり
// 引数の省略かつ、ネストを減らしたシンプルな見た目
UIView.animate(withDuration: 0.1) {
self.view.backgroundColor = .red
}
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// Swift5.2
// Trailing Closureなし
UIView.animate(withDuration: 0.3, animations: {
self.view.alpha = 0
}, completion: { _ in
self.view.removeFromSuperview()
})
Multiple trailing closures SE-0279
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// Trailing Closureあり
// 引数名が省略されていて2つ目のclosureが
// わかりにくい
UIView.animate(withDuration: 0.3, animations: {
self.view.alpha = 0
}) { _ in
self.view.removeFromSuperview()
}
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// Swift5.2
// Multiple Trailing Closureなし
// 引数名が省略されいて
2つ目のclosureがわかりにくい
UIView.animate(withDuration: 0.3, animations: {
view.alpha = 0
}) { _ in
view.removeFromSuperview()
}
Multiple trailing closures SE-0279
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// Swift5.3
// Multiple trailing closureをつかうと…
// 少ないネストかつ、2つ目のclosureの引数もあるので
// わかりやすい
UIView.animate(withDuration: 0.3) {
view.alpha = 0
} completion: { _ in
view.removeFromSuperview()
}
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// もっとmultiple trailing closures...
func animate(animation: (() -> Void), preparation: (() -> Void), completion: ((Bool) -> Void)) {
// hoge hoge...
}
animate {
// animating...
} preparation: {
// preparing...
} completion: { result in
// completing task...
}
Multiple trailing closures SE-0279
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// たくさんのself...
UIView.animate(withDuration: 0.3) {
self.recordingView?.alpha = 0.0
self.textView.alpha = 1.0
} completion: { _ in
self.activeTransitionCount -= 1
if !self.isRecording && self.activeTransitionCount == 0 {
self.recordingView?.removeFromSuperview()
self.recordingView = nil
}
}
Increased availability of implicit self in
closures SE-0269
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Increased availability of implicit self in
closures SE-0269
// Swift5.3ではselfをキャプチャすればclosure内で
// 省略できる
UIView.animate(withDuration: 0.3) { [self] in
recordingView?.alpha = 0.0
textView.alpha = 1.0
} completion: { [self] _ in
activeTransitionCount -= 1
if !isRecording && activeTransitionCount == 0 {
recordingView?.removeFromSuperview()
recordingView = nil
}
}
// たくさんのself…
UIView.animate(withDuration: 0.3) {
self.recordingView?.alpha = 0.0
self.textView.alpha = 1.0
} completion: { _ in
self.activeTransitionCount -= 1
if !self.isRecording && self.activeTransitionCount == 0 {
self.recordingView?.removeFromSuperview()
self.recordingView = nil
}
}
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Increased availability of implicit self in
closures SE-0269
// weak selfは今まで通りです
UIView.animate(withDuration: 0.3) { [weak self] in
guard let self = self else { return }
self.recordingView?.alpha = 0.0
self.textView.alpha = 1.0
}
UIView.animate(withDuration: 0.3) { [weak self] in
self?.recordingView?.alpha = 0.0
self?.textView.alpha = 1.0
}
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Increased availability of implicit self in
closures SE-0269
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Synthesized Comparable conformance for enum types SE-0266
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// まずComparableとは?
struct Date {
let year: Int
let month: Int
let day: Int
}
extension Date: Comparable {
static func < (lhs: Date, rhs: Date) -> Bool {
if lhs.year != rhs.year {
return lhs.year < rhs.year
} else if lhs.month != rhs.month {
return lhs.month < rhs.month
} else {
return lhs.day < rhs.day
}
}
}
print(Date(year: 10, month: 10, day: 10) > Date(year: 10, month: 10, day: 9)) // true
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Synthesized comparable conformance for
enum types SE-0266
// Swift 5.3未満
enum Membership: Int, Comparable {
case basic
case silver
case gold
static func < (lhs: Self, rhs: Self) -> Bool {
return lhs.rawValue < rhs.rawValue
}
}
print(Membership.basic < Membership.silver) // true
print(Membership.silver < Membership.gold) // true
print(Membership.basic > Membership.gold) // false
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Synthesized comparable conformance for
enum types SE-0266
// Swift 5.3以前
enum Membership: Int, Comparable {
case basic
case silver
case gold
static func < (lhs: Self, rhs: Self) -> Bool {
return lhs.rawValue < rhs.rawValue
}
}
print(Membership.basic < Membership.silver) // true
print(Membership.silver < Membership.gold) // true
print(Membership.basic > Membership.gold) // false
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// Swift 5.3では簡略化できる
enum Membership: Comparable {
case basic
case silver
case gold
}
print(Membership.basic < Membership.silver) // true
print(Membership.silver < Membership.gold) // true
print(Membership.basic > Membership.gold) // false
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Enum cases as protocol witnesses SE-0280
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Enum cases as protocol witnesses SE-0280
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KeyPath expressions as function SE-0249
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KeyPath expressions as function SE-0249
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KeyPath expressions as function SE-0249
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KeyPath expressions as function SE-0249
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Swift 5.2からは必要ない
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1. Multiple trailing closures
複数クロージャーでもカッコを省略して引数に書ける！
2. Increased availability of implicit self in closures
selfを書く回数が減る！
3. Synthesized Comparable conformance for enum types
enumにComparableプロトコルが使いやすくなった！
4. Enum cases as protocol witnesses
Enum caseでstatic var・static funcを満たすことができる！
5. KeyPath expressions as function
keyPathをクロージャーの代わりに渡せる！
おさらい
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Thank you
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