差分計算アルゴリズムを用いた高速なUITableView描画

by fumito-ito

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1 ࠩ෼ܭࢉΞϧΰϦζϜΛ༻͍ ͨߴ଎ͳ UITableView ඳը

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2 ύϑΥʔϚϯε ؾʹͯ͠·͔͢ʁ

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3 “Most apps target a frame rate of 60 FPS, Equivalent to 16.67 ms per frame.” https://developer.apple.com/library/archive/documentation/3DDrawing/Conceptual/ MTLBestPracticesGuide/FrameRate.html

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4 16 ms…

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5 UITableView͕େྔʹฒͿ

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6 UITableViewΛ ଎͍ͨ͘͠

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7 UITableViewΛ଎͘͢Δʹ͸ • CellͷϨϯμϦϯά࠷దԽ • ඇಉظͳσʔλϑΣονͱΩϟογϡ • ඇಉظͳը૾ϩʔυͱΩϟογϡ • ΦϑϨϯμϦϯάΛආ͚Δ • αΠζͷࣄલܭࢉͱΩϟογϡ

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8 ඳը͢Δߦ͕গͳ͚Ε ͹଎͍ͷͰ͸…

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9 performBatchUpdates

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10 ࠩ෼ߋ৽Λߦ͏ͨΊʹ͸ • มߋલͷσʔλΛมߋޙͷσʔλʹม׵͢ΔͨΊͷ  ฤूૢ࡞Λܭࢉ͠ͳͯ͘͸ͳΒͳ͍ • มߋલޙͷσʔλͷ௕͞ΛͦΕͧΕM, Nͱͨ͠৔߹  ૯౰ͨΓͰܭࢉྔ͸O(M * N)ʹͳΔ • ฤूૢ࡞Λܭࢉ͢Δํ๏͸͢Ͱʹଟ͘ͷΞϧΰϦζϜ͕  ߟҊ͞Ε͓ͯΓɺ͜ΕΒΛ༻͍Δ͜ͱͰܭࢉྔΛখ͘͞  ͢Δ͜ͱ͕Ͱ͖Δ

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11 ͬ͘͟Γฤूૢ࡞ܭࢉ ΞϧΰϦζϜ

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X ͬ͘͟Γฤूڑ཭ΞϧΰϦζϜ • จࣈྻͷฤूૢ࡞Λάϥϑʹϓ ϩοτ͠ɺ࠷খૢ࡞ύεʢฤू ڑ཭ʣΛ୳͢ • ૯ίετΛԾఆͯ͠࠷খίετ Λ୳ࡧ͢Δํ๏ʢMyerʣ • ࡟আૢ࡞ͷ૯਺ΛԾఆͯ͠࠷খ ίετΛ୳ࡧ͢Δํ๏ʢWuʣ https://susisu.hatenablog.com/entry/2017/10/09/134032

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X ͬ͘͟ΓHeckel๏ • ྆ํͷཁૉྻʹݱΕΔڞ௨͔ͭ  ̍౓͔͠ग़ݱ͠ͳ͍ཁૉΛ୳͢ • நग़ͨ͠ߦΛى఺ʹڞ௨ϒϩοΫ Λ୳ͯࠩ͠෼͔ΒऔΓআ͘ Paul Heckel (Apr 1978), “A technique for isolating differences between files”

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12 ֤ΞϧΰϦζϜͷܭࢉྔ • Myer๏ • ܭࢉྔɿO(N + D^2) ~ O(N * D) • D͸ฤूڑ཭ʢฤूૢ࡞ͷ਺ʣ • Wu๏ • ܭࢉྔɿO(N + P * D) ~ O(N * P) • P͸࡟আૢ࡞ͷ਺ɺD͸ฤूڑ཭ • Heckel๏ • ܭࢉྔɿO(N)

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13 ฤूૢ࡞ܭࢉΞϧΰϦζϜͷ࣮૷ • Dwifft • EditDistance • RxDataSources • DifferenceKit

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14 Dwifft • https://github.com/jflinter/Dwifft • Myer๏ͬΆ͍࣮૷ => O(N * D) • ࠓճऔΓ্͛ͨ΋ͷͷதͰ͸ʢཧ࿦తʹ͸ʣҰ൪஗͍

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15 EditDistance • https://github.com/kazuhiro4949/EditDistance • Wu๏ͬΆ͍࣮૷ => O(N * P) • WuͷΞϧΰϦζϜΛ࣮૷͍ͯ͠Δ΋ͷ͸ҙ֎ͱগͳ͍

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16 RxDataSources • https://github.com/RxSwiftCommunity/RxDataSources • Heckel๏ + α => O(N) • IGListKit΋ಉ༷ʹHeckel๏Λ࠾༻͍ͯ͠Δ͕ɺ  ΑΓ࠷దԽ͞Ε͍ͯΔRxDataSourceΛ࠾༻͢Δ • ࠩ෼ܭࢉΞϧΰϦζϜ෦෼͸ Differentiator.framework  ͱͯ͠෼཭͞Ε͍ͯΔͷͰଞͷϑϨʔϜϫʔΫ͔Β  ར༻͢Δ͜ͱ͕ՄೳͰ͋Δ

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18 DifferenceKit • https://github.com/ra1028/DifferenceKit • Heckel๏ + α => O(N) • iOSDC1ϲ݄લʹಥ೗ͱͯ͠ݱΕͨ৽੕

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20 ύϑΥʔϚϯεൺֱ

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21 ϨΪϡϨʔγϣϯ • Insert 10% + Delete 10% • ཁૉ਺: 1,000 • ཁૉ਺: 10,000 • Insert 30% + Delete 30% • ཁૉ਺: 1,000 • ཁૉ਺: 10,000

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22 ύϑΥʔϚϯεൺֱ(1,000ߦ)

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23 ύϑΥʔϚϯεൺֱ(10,000ߦ)

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24 ࠩ෼ߋ৽ύϑΥʔϚϯε(1,000ߦ)

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25 ࠩ෼ߋ৽ύϑΥʔϚϯε(100ߦ)

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26 ಈ͔ͤΔαϯϓϧ • https://github.com/fumito-ito/iOSDC-2018-Sample

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27 ύϑΥʔϚϯεҎ֎ͷൺֱ؍఺ • ଟ࣍ݩ഑ྻʹରԠ͍ͯ͠Δ͔ • ≒ ηΫγϣϯͷαϙʔτ • ॏෳͨ͠σʔλΛڐ༰͢Δ͔ • UITableViewͰදݱՄೳͳૢ࡞Λαϙʔτ͍ͯ͠Δ͔

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28 ϥΠϒϥϦͷػೳൺֱ

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29 ೔ܦిࢠ൛ͷࠩ෼ܭࢉ • RxASDataSourceΛ࠾༻ͨ͠ • RxDataSourcesͷޓ׵ϥΠϒϥϦ • ΋ͱ΋ͱར༻͍ͯͨ͠RxSwiftɺTextureͱ૬ੑͷ͍͍  ϥΠϒϥϦΛ࢖͍͔ͨͬͨ

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30 ೔ܦిࢠ൛Ͱͷվળྫ reloadData ࠩ෼ߋ৽

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31 ࠩ෼ߋ৽ ຊ౰ʹ΍Δ΂͖ʁ

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32 ࠩ෼ߋ৽͸ίετʹݟ߹ͬͯΔʁ • ཁૉ਺ʹൺྫͯ͠ܭࢉίετ͕૿େ͢Δ͸ͣ • ࣮ࡍʹηϧͷ਺͕େ͖͗͢Δ৔߹͸ඇৗʹ஗͘ͳΔ  ໰୊͕ࢦఠ͞Ε͍ͯΔ • “I have a huge data set and - performBatchUpdatesAnimated: completion: is super slow. What do I do?”  - IGListKit, performBatchUpdates long perform on main thread #803  https://github.com/Instagram/IGListKit/issues/ 803#issuecomment-305276659

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33 ؾʹͳΔํ͸ͪ͜Β • ʮ5000ߦͷUITableViewΛࠩ෼ߋ৽͢Δʯ • 2018/09/01 14:20 ~ @Track A • https://fortee.jp/iosdc-japan-2018/proposal/ 530b6839-cc50-452c-9682-897afa9db18c

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34 ·ͱΊ • ࠩ෼ߋ৽Λ༻͍Δ͜ͱͰUITableViewΛߴ଎ʹ  ඳը͢Δ͜ͱ͕Ͱ͖Δ • ࠩ෼ͷܭࢉʹΞϧΰϦζϜΛద༻͢Δ͜ͱͰܭࢉྔΛ  ݮΒ͠ɺύϑΥʔϚϯεΛ޲্ͤ͞Δ͜ͱ͕Ͱ͖Δ • දࣔ͢Δσʔλͷྔ͕େ͖͍৔߹͸ࠩ෼ܭࢉΛ͢Δͷ͔ɺ reloadDataΛ͢Δͷ͔ߟ͑ͨํ͕ྑ͍

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35 RxASDataSourceͷ ίϯτϦϏϡʔλʔ ืूதͰ͢ɻ @fumito_ito fumito-ito

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36 ग़య • Paul Heckel (Apr 1978), “A technique for isolating differences between files” • James W. Hunt, M. Douglas Mcllory (Jun 1976), “An Algorithm for Differential File Comparison” • E. Myers (1986), “An O(ND) Difference Algorithm and Its Variations”