Meet AsyncSequence

"TZOD4FRVFODF ͬͯͳʹʁ Ӊࠤݟެี 1/16

Ӊࠤݟެีʢ!VTBNJLʣ w 鳍鲟鳫鳢鳣גࣜձࣾJ04鲠鳫鲰鳃鲚鲾鲻鲧鳢鱅鳁 w ٕज़ಉਓࢽ w $PNCJOF鲗鱴鱝鲆鲍鱋 w $PNCJOF鱭6*,JU鱰鲍鲐J04鲚鳏鳢։ൃ w
هࣄࣥච༧ఆ w J04%$+BQBO$PNCJOF0QFSBUPS鲤鲜鳁 2/16

4XJGU$PODVSSFODZ w ඇಉظॲཧ鱑࣮૷鱜鲉鱞鱔鱯鲐ʢJ04Ҏ߱ʣ w asyncawait w 4USVDUVSFE$PODVSSFODZ w "DUPS w
ࠓճ鱴asyncawait鱳࿩ 3/16

BTZODBXBJUΛ࢖Θͳ͍৔߹ func fetchThumbnail(completion: (UIImage?, Error?) -> Void) { let task
= URLSession.shared.dataTask(with: request) { ... if let error = error { completion(nil, error) } else { // ... data / response ͷॲཧ ... completion(thumbnail, nil) } } task.resume() } 4/16

BTZODBXBJUΛ࢖͏৔߹ func fetchThumbnail() async throws -> UIImage { let (data,
response) = try await URLSession.shared.data(for: request) // ... data / response ͷॲཧ ... return thumbnail } w await鱳Օॴ鱬鲭鲱鳒鳫鳁ɺॲཧ鱑ऴ鲔鱨鱤鲎෮ؼ 5/16

63-4FTTJPOͷϝιου // async / await ඇରԠ൛ func dataTask(with request: URLRequest,
completionHandler: (Data?, URLResponse?, Error?) -> Void) -> URLSessionDataTask // async / await ରԠ൛ func data(for request: URLRequest) async throws -> (Data, URLResponse) 6/16

"TZOD4FRVFODFͱ͸ w Sequence鱳asyncawaitରԠ൛ w 鱮鱋鱉鱋鱘鱭ʁ w 鲃鱟Sequence鱳鱏鱚鲎鱉 7/16

4FRVFODF w Sequence鳏鳥鳀鲫鳣鱰४ڌ鱜鱤ܕ鱬鱴ɾɾɾ w for-inߏจ鱑࢖鱍鲐 w ஋鱴ಉظత鱰౉鱚鲑鲐 for quake in
quakes { // ... quake ͷॲཧ ... } 8/16

"TZOD4FRVFODF w AsyncSequence鳏鳥鳀鲫鳣鱰४ڌ鱜鱤ܕ鱬鱴ɾɾɾ w for-await-inߏจ鱑࢖鱍鲐 w ஋鱴ඇಉظత鱰౉鱚鲑鲐 for await quake
in quakes { // ... quake ͷॲཧ ... } 9/16

4FRVFODFΛΠςϨʔλͰݟΔ for quake in quakes { // ... quake ͷॲཧ
... } var iterator = quakes.makeIterator() while let quake = iterator.next() { // ... quake ͷॲཧ ... } 10/16

"TZOD4FRVFODFΛΠςϨʔλͰݟΔ for await quake in quakes { // ... quake
ͷॲཧ ... } var iterator = quakes.makeAsyncIterator() while let quake = await iterator.next() { // ... quake ͷॲཧ ... } 11/16

"TZOD4FRVFODFΦϖϨʔλ let strings = quakes.map { (quake) -> String in
// ... quake Λ String ʹม׵ ... } for await string in strings { // ... string ͷॲཧ ... } 12/16

"TZOD4FRVFODFͷฒྻॲཧ let task1 = async { for await quake in
quakes { // ... quake ͷॲཧ ... } } let task2 = async { for await string in strings { // ... string ͷॲཧ ... } } // task1.cancel() 13/16

$PNCJOFͱͷൺֱ w AsyncSequence鱴$PNCJOF鱭ѻ鱋໰୊ྖҬ鱑ࣅ鱫鱉鲐 w AsyncSequence w J04Ҏ߱ɺݴޠ૊鲄ࠐ鲄ߏจɺ鲯鳫鳏鳣鱬෼鱐鲏鲉鱞鱉 w $PNCJOF w
J04Ҏ߱ɺ鲢鳒鳤鱅鲷鱑๛෋ɺෳ਺鲱鳀鳢鱅鳘鱳鳖鱅鲰 14/16

ࠓޙ͸Ͳ͏ͳΔʁ w ڞଘʁ w $鱬鱴asyncawait鱭3Y鱑ࠞࡏ鱜鱫࢖鲔鲑鱫鱉鲐 w ༥߹ʁ w ࢓༷ࡦఆத鱳AsyncStream鱑鱏ޓ鱉鲗༥߹鱞鲐鱐鲇ʁ w
ݱ࣌఺鱬鱴鱮鱦鲎鱭鲇鱉鱍鱯鱉 15/16

ࢀߟ৘ใ w 88%$鲳鲻鲯鳟鳫.FFU"TZOD4FRVFODF w "1*鳢鳍鲙鳤鳫鲱AsyncSequence鳏鳥鳀鲫鳣 16/16

Meet AsyncSequence

Meet AsyncSequence

USAMI Kosuke

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"TZOD4FRVFODF ͬͯͳʹʁ Ӊࠤݟެี 1/16

Ӊࠤݟެีʢ!VTBNJLʣ w 鳍鲟鳫鳢鳣גࣜձࣾJ04鲠鳫鲰鳃鲚鲾鲻鲧鳢鱅鳁 w ٕज़ಉਓࢽ w $PNCJOF鲗鱴鱝鲆鲍鱋 w $PNCJOF鱭6*,JU鱰鲍鲐J04鲚鳏鳢։ൃ w

4XJGU$PODVSSFODZ w ඇಉظॲཧ鱑࣮૷鱜鲉鱞鱔鱯鲐ʢJ04Ҏ߱ʣ w asyncawait w 4USVDUVSFE$PODVSSFODZ w "DUPS w

BTZODBXBJUΛ࢖Θͳ͍৔߹ func fetchThumbnail(completion: (UIImage?, Error?) -> Void) { let task

BTZODBXBJUΛ࢖͏৔߹ func fetchThumbnail() async throws -> UIImage { let (data,

63-4FTTJPOͷϝιου // async / await ඇରԠ൛ func dataTask(with request: URLRequest,

"TZOD4FRVFODFͱ͸ w Sequence鱳asyncawaitରԠ൛ w 鱮鱋鱉鱋鱘鱭ʁ w 鲃鱟Sequence鱳鱏鱚鲎鱉 7/16

4FRVFODF w Sequence鳏鳥鳀鲫鳣鱰४ڌ鱜鱤ܕ鱬鱴ɾɾɾ w for-inߏจ鱑࢖鱍鲐 w ஋鱴ಉظత鱰౉鱚鲑鲐 for quake in

"TZOD4FRVFODF w AsyncSequence鳏鳥鳀鲫鳣鱰४ڌ鱜鱤ܕ鱬鱴ɾɾɾ w for-await-inߏจ鱑࢖鱍鲐 w ஋鱴ඇಉظత鱰౉鱚鲑鲐 for await quake

4FRVFODFΛΠςϨʔλͰݟΔ for quake in quakes { // ... quake ͷॲཧ

"TZOD4FRVFODFΛΠςϨʔλͰݟΔ for await quake in quakes { // ... quake

"TZOD4FRVFODFΦϖϨʔλ let strings = quakes.map { (quake) -> String in

"TZOD4FRVFODFͷฒྻॲཧ let task1 = async { for await quake in

$PNCJOFͱͷൺֱ w AsyncSequence鱴$PNCJOF鱭ѻ鱋໰୊ྖҬ鱑ࣅ鱫鱉鲐 w AsyncSequence w J04Ҏ߱ɺݴޠ૊鲄ࠐ鲄ߏจɺ鲯鳫鳏鳣鱬෼鱐鲏鲉鱞鱉 w $PNCJOF w

ࠓޙ͸Ͳ͏ͳΔʁ w ڞଘʁ w $鱬鱴asyncawait鱭3Y鱑ࠞࡏ鱜鱫࢖鲔鲑鱫鱉鲐 w ༥߹ʁ w ࢓༷ࡦఆத鱳AsyncStream鱑鱏ޓ鱉鲗༥߹鱞鲐鱐鲇ʁ w

ࢀߟ৘ใ w 88%$鲳鲻鲯鳟鳫.FFU"TZOD4FRVFODF w "1*鳢鳍鲙鳤鳫鲱AsyncSequence鳏鳥鳀鲫鳣 16/16