SwiftのStringの文字の数え方を完全理解する

SwiftはUnicodeの扱いに非常に長けた言語であり、絵文字を含む文字列でも正しい文字数を計算してくれます。
その反面、Unicodeの複雑さに引きずられてしまい、直感的な操作ができない時もあります。たとえば、 string[2] と書いても3番目の文字を取得することはできません。

そんな複雑なところのあるSwiftの文字列処理ですが、複雑なものを受け入れてきちんと理解するのはそこまで難しいものではありません。

このトークでは、Unicodeとの関係を意識しながら、Swiftの文字数の扱い方とその裏にある考え方を解説します。

Transcript

1. SwiftͷStringͷจࣈͷ ਺͑ํΛ׬શཧղ͢Δ Takanori Hirobe @taka1068
2. • ኍ෦ وಙ • ϑΣϯϦϧגࣜձࣾॴଐ ࣗݾ঺հ
3. ࣗݾ঺հ • ኍ෦ وಙ • ϑΣϯϦϧגࣜձࣾॴଐ ΰʔϧυεϙϯαʔ
4. ࣗݾ঺հ • ኍ෦ وಙ • ϑΣϯϦϧגࣜձࣾॴଐ ΰʔϧυεϙϯαʔ Ϙτϧ΢Υʔλʔεϙϯαʔ
5. ࣗݾ঺հ • ኍ෦ وಙ • ϑΣϯϦϧגࣜձࣾॴଐ ΰʔϧυεϙϯαʔ Ϙτϧ΢Υʔλʔεϙϯαʔ
6. ΞδΣϯμ - SwiftͷStringʹ͍ͭͯ - Unicodeʹ͍ͭͯ - Stringͱཁૉͷஔ͖׵͑ʹ͍ͭͯ
7. ΞδΣϯμ -SwiftͷStringʹ͍ͭͯ - Unicodeʹ͍ͭͯ - Stringͱཁૉͷஔ͖׵͑ʹ͍ͭͯ
8. print("Hello, iOSDC!")
9. String
10. String Value Type Bridges to NSString
11. String Value Type UTF-8 Encoded Hashable Bridges to NSString
12. String Value Type UTF-8 Encoded Equatable Hashable Bridges to NSString Collection
13. String Value Type UTF-8 Encoded Equatable Hashable Bridges to NSString Collection
14. Collection
15. Collection let array = [10, 20, 30, 40, 50] let string = "abc͍͋͏͓͑"
16. Collection let array = [10, 20, 30, 40, 50] let string = "abc͍͋͏͓͑" let first = array[0]
17. Collection let array = [10, 20, 30, 40, 50] let string = "abc͍͋͏͓͑" let first = array[0] let first = array[array.startIndex] or better
18. Collection let array = [10, 20, 30, 40, 50] let string = "abc͍͋͏͓͑" let first = array[0]
19. Collection let array = [10, 20, 30, 40, 50] let string = "abc͍͋͏͓͑" let first = array[0] Int ഑ྻͷཁૉͷܕ
20. Collection let array = [10, 20, 30, 40, 50] let string = "abc͍͋͏͓͑" ఴࣈΞΫηε: Int ཁૉͷܕ: Int
21. Collection let array = [10, 20, 30, 40, 50] let string = "abc͍͋͏͓͑" ఴࣈΞΫηε: Int ཁૉͷܕ: Int let first = string[0]
22. Collection let array = [10, 20, 30, 40, 50] let string = "abc͍͋͏͓͑" ఴࣈΞΫηε: Int ཁૉͷܕ: Int let first = string[0]
23. Collection let array = [10, 20, 30, 40, 50] let string = "abc͍͋͏͓͑" ఴࣈΞΫηε: Int ཁૉͷܕ: Int let first = string[string.startIndex]
24. Collection let array = [10, 20, 30, 40, 50] let string = "abc͍͋͏͓͑" ఴࣈΞΫηε: Int ཁૉͷܕ: Int let first = string[string.startIndex] String.Index Character
25. Collection let array = [10, 20, 30, 40, 50] let string = "abc͍͋͏͓͑" ఴࣈΞΫηε: Int ཁૉͷܕ: Int let startIdx = str.startIndex let index = str.index(startIdx, offsetBy: 5) let fifthChar = str[index]
26. Collection let array = [10, 20, 30, 40, 50] let string = "abc͍͋͏͓͑" ఴࣈΞΫηε: Int ཁૉͷܕ: Int let startIdx = str.startIndex let index = str.index(startIdx, offsetBy: 5) let fifthChar = str[index]
27. Collection let array = [10, 20, 30, 40, 50] let string = "abc͍͋͏͓͑" ఴࣈΞΫηε: Int ཁૉͷܕ: Int ఴࣈΞΫηε: String.Index ཁૉͷܕ: Character
28. Collection var array = [ , 20, 30, 40, 50] var string = “ bc͍͋͏͓͑” ఴࣈΞΫηε: Int ཁૉͷܕ: Int ఴࣈΞΫηε: String.Index ཁૉͷܕ: Character 10 Λ 100 ʹม͑Δ a Λ X ʹม͑Δ a 10
29. Collection X 100 var array = [ , 20, 30, 40, 50] var string = “ bc͍͋͏͓͑” ఴࣈΞΫηε: Int ཁૉͷܕ: Int ఴࣈΞΫηε: String.Index ཁૉͷܕ: Character
30. Collection var array = [100, 20, 30, 40, 50] var string = "Xbc͍͋͏͓͑" ఴࣈΞΫηε: Int ཁૉͷܕ: Int ఴࣈΞΫηε: String.Index ཁૉͷܕ: Character array[0] = 100
31. Collection var array = [100, 20, 30, 40, 50] var string = "Xbc͍͋͏͓͑" ఴࣈΞΫηε: Int ཁૉͷܕ: Int ఴࣈΞΫηε: String.Index ཁૉͷܕ: Character array[0] = 100 "
32. Collection var array = [100, 20, 30, 40, 50] var string = "Xbc͍͋͏͓͑" ఴࣈΞΫηε: Int ཁૉͷܕ: Int ఴࣈΞΫηε: String.Index ཁૉͷܕ: Character
33. Collection var array = [100, 20, 30, 40, 50] var string = "Xbc͍͋͏͓͑" ఴࣈΞΫηε: Int ཁૉͷܕ: Int ఴࣈΞΫηε: String.Index ཁૉͷܕ: Character string[string.startIndex] = "X"
34. Collection var array = [100, 20, 30, 40, 50] var string = "Xbc͍͋͏͓͑" ఴࣈΞΫηε: Int ཁૉͷܕ: Int ఴࣈΞΫηε: String.Index ཁૉͷܕ: Character string[string.startIndex] = "X" #
35. Collection let array = [10, 20, 30, 40, 50] let string = "abc͍͋͏͓͑" ఴࣈΞΫηε: Int ཁૉͷܕ: Int ఴࣈʹΑΔมߋ: OK ఴࣈΞΫηε: String.Index ཁૉͷܕ: Character ఴࣈʹΑΔมߋ: NG
36. Collection let array = [10, 20, 30, 40, 50] let string = "abc͍͋͏͓͑" ఴࣈΞΫηε: Int ཁૉͷܕ: Int ఴࣈʹΑΔมߋ: OK ఴࣈΞΫηε: String.Index ཁૉͷܕ: Character ఴࣈʹΑΔมߋ: NG
37. Collection let array = [10, 20, 30, 40, 50] let string = "abc͍͋͏͓͑" ఴࣈΞΫηε: Int ཁૉͷܕ: Int ఴࣈʹΑΔมߋ: OK ఴࣈΞΫηε: String.Index ཁૉͷܕ: Character ఴࣈʹΑΔมߋ: NG
38. Collection let array = [10, 20, 30, 40, 50] let string = "abc͍͋͏͓͑" ఴࣈΞΫηε: Int ཁૉͷܕ: Int ఴࣈʹΑΔมߋ: OK ఴࣈΞΫηε: String.Index ཁૉͷܕ: Character ఴࣈʹΑΔมߋ: NG count͸5 count͸8
39. Collection let array = [10, 20, 30, 40, 50] let string = "abc͍͋͏͓͑" ఴࣈΞΫηε: Int ཁૉͷܕ: Int ఴࣈʹΑΔมߋ: OK ఴࣈΞΫηε: String.Index ཁૉͷܕ: Character ఴࣈʹΑΔมߋ: NG
40. ಉ͡Collectionͱ͍ͬͯ΋ѻ͍ํ ͕গ͠ҧ͏ - Stringͷํ͕ѻ͍ʹ͍͘
41. ΞδΣϯμ - SwiftͷStringʹ͍ͭͯ -Unicodeʹ͍ͭͯ - Stringͱཁૉͷஔ͖׵͑ʹ͍ͭͯ
42. ʮͺʯͱ͍͏จࣈΛ
 UnicodeͰද͢ ྫ
43. ͺ ͺ let pa1 = “…” let pa2 = “…” print(pa1, pa2) // ͺ ͺ
44. ͺ ͺ let pa1 = “…” let pa2 = “…” print(pa1, pa2) // ͺ ͺ
45. ͺ ͺ จࣈ ͺ ͺ Unicode
 Scalar ͺ U+3071 ͸ U+306F
    㿇 U+309A
46. จࣈ ͺ ͺ Unicode
 Scalar ͺ U+3071 ͸ U+306F
    㿇 U+309A
47. จࣈ ͺ ͺ Unicode
 Scalar ͺ U+3071 ͸ U+306F
    㿇 U+309A ʮͺʯΛද͢εΧϥ஋(͋Δछͷූ߸)୯ମͰʮͺʯΛද͢
48. จࣈ ͺ ͺ Unicode
 Scalar ͺ U+3071 ͸ U+306F
    㿇 U+309A
49. จࣈ ͺ ͺ Unicode
 Scalar ͺ U+3071 ͸ U+306F
    㿇 U+309A ʮ͸ʯͱʮ
    㿇 ʯΛ૊Έ߹ΘͤͯʮͺʯΛද͢ɻ
50. จࣈ ͺ ͺ Unicode
 Scalar ͺ U+3071 ͸ U+306F
    㿇 U+309A
51. จࣈ ͺ ͺ Unicode
 Scalar ͺ U+3071 ͸ U+306F
    㿇 U+309A
52. จࣈ ͺ ͺ Unicode
 Scalar ͺ U+3071 ͸ U+306F
    㿇 U+309A
53. จࣈ ͺ ͺ Unicode
 Scalar ͺ U+3071 ͸ U+306F
    㿇 U+309A
54. จࣈ ͺ ͺ Unicode
 Scalar ͺ U+3071 ͸ U+306F
    㿇 U+309A
55. จࣈ ͺ ͺ Unicode
 Scalar ͺ U+3071 ͸ U+306F
    㿇 U+309A
56. จࣈ ͺ ͺ Unicode
 Scalar ͺ U+3071 ͸ U+306F
    㿇 U+309A
57. จࣈ ͺ ͺ Unicode
 Scalar ͺ U+3071 ͸ U+306F
    㿇 U+309A
58. จࣈ ͺ ͺ Unicode
 Scalar ͺ U+3071 ͸ U+306F
    㿇 U+309A
59. จࣈ ͺ ͺ Unicode
 Scalar ͺ U+3071 ͸ U+306F
    㿇 U+309A
60. จࣈ ͺ ͺ Unicode
 Scalar ͺ U+3071 ͸ U+306F
    㿇 U+309A
65. จࣈ $ & Unicode
 Scalar U+1F469 U+200D U+1F692 U+1F3E3 U+1F1EF U+1F1F5
66. จࣈ $ & Unicode
 Scalar U+1F469 U+200D U+1F692 U+1F3E3 U+1F1EF U+1F1F5
67. ֦ுॻهૉΫϥελ
68. ֦ுॻهૉΫϥελ • ӳޠͰ͸ Extended Grapheme Cluster
69. https://developer.apple.com/documentation/swift/character
70. https://developer.apple.com/documentation/swift/character
71. https://developer.apple.com/documentation/swift/character
72. https://developer.apple.com/documentation/swift/character
73. ֦ுॻهૉΫϥελ • ӳޠͰ͸ Extended Grapheme Cluster • SwiftͷCharacterܕʹ֘౰
74. ֦ுॻهૉΫϥελ • ӳޠͰ͸ Extended Grapheme Cluster • SwiftͷCharacterܕʹ֘౰ • Ϣʔβʔʹͱͬͯͷʮ1จࣈʯ
75. "\r\n"͸1จࣈ
76. https://unicode.org/reports/tr29/#Grapheme_Cluster_Boundaries
77. งғؾΛײͯ͡ΈΔ
78. งғؾΛײͯ͡ΈΔ "ͺa\r\n&"
79. U+306F U+309A U+0A U+1F146 U+200D U+1F692 U+61 U+0D จࣈ ͺ a \r \n & Unicode
 Scalar U+306F U+309A U+61 U+0D U+0A U+1F1EF U+1F1F5
80. U+306F U+309A U+0A U+1F146 U+200D U+1F692 U+61 U+0D จࣈ ͺ a \r \n & Unicode
 Scalar U+306F U+309A U+61 U+0D U+0A U+1F1EF U+1F1F5 1 2 3 4
81. U+306F U+309A U+0A U+1F146 U+200D U+1F692 U+61 U+0D จࣈ ͺ a \r \n & Unicode
 Scalar U+306F U+309A U+61 U+0D U+0A U+1F1EF U+1F1F5
82. U+309A U+0A U+1F146 U+200D U+1F692 U+61 U+0D จࣈ ͺ a \r \n & Unicode
 Scalar U+306F U+309A U+61 U+0D U+0A U+1F1EF U+1F1F5 U+306F
83. U+309A U+0A U+1F146 U+200D U+1F692 U+61 U+0D จࣈ ͺ a \r \n & Unicode
 Scalar U+306F U+309A U+61 U+0D U+0A U+1F1EF U+1F1F5 U+306F: ͻΒ͕ͳͷʮ͸ʯ
84. U+309A U+0A U+1F146 U+200D U+1F692 U+61 U+0D จࣈ ͺ a \r \n & Unicode
 Scalar U+306F U+309A U+61 U+0D U+0A U+1F1EF U+1F1F5 U+306F: ͻΒ͕ͳͷʮ͸ʯ
85. U+309A U+0A U+1F146 U+200D U+1F692 U+61 U+0D จࣈ ͺ a \r \n & Unicode
 Scalar U+306F U+309A U+61 U+0D U+0A U+1F1EF U+1F1F5 U+306F: ͻΒ͕ͳͷʮ͸ʯ
86. U+309A: ʮ ʄʯ U+0A U+1F146 U+200D U+1F692 U+61 U+0D จࣈ ͺ a \r \n & Unicode
 Scalar U+306F U+309A U+61 U+0D U+0A U+1F1EF U+1F1F5 U+306F: ͻΒ͕ͳͷʮ͸ʯ
87. U+309A: ʮ ʄʯ U+0A U+1F146 U+200D U+1F692 U+61 U+0D จࣈ ͺ a \r \n & Unicode
 Scalar U+306F U+309A U+61 U+0D U+0A U+1F1EF U+1F1F5 U+306F: ͻΒ͕ͳͷʮ͸ʯ Nonspacing Mark
88. U+61 U+309A: ʮ ʄʯ U+0A U+1F146 U+200D U+1F692 U+0D จࣈ ͺ a \r \n & Unicode
 Scalar U+306F U+309A U+61 U+0D U+0A U+1F1EF U+1F1F5 U+306F: ͻΒ͕ͳͷʮ͸ʯ
89. U+61 U+309A: ʮ ʄʯ U+0A U+1F146 U+200D U+1F692 U+0D จࣈ ͺ a \r \n & Unicode
 Scalar U+306F U+309A U+61 U+0D U+0A U+1F1EF U+1F1F5 U+306F: ͻΒ͕ͳͷʮ͸ʯ
90. U+61: ʮaʯ U+309A: ʮ ʄʯ U+0A U+1F146 U+200D U+1F692 U+0D จࣈ ͺ a \r \n & Unicode
 Scalar U+306F U+309A U+61 U+0D U+0A U+1F1EF U+1F1F5 U+306F: ͻΒ͕ͳͷʮ͸ʯ
91. U+61: ʮaʯ U+309A: ʮ ʄʯ U+0A U+1F146 U+200D U+1F692 U+0D จࣈ ͺ a \r \n & Unicode
 Scalar U+306F U+309A U+61 U+0D U+0A U+1F1EF U+1F1F5 U+306F: ͻΒ͕ͳͷʮ͸ʯ ͺ
92. U+61: ʮaʯ U+0A U+1F146 U+200D U+1F692 U+0D จࣈ ͺ a \r \n & Unicode
 Scalar U+306F U+309A U+61 U+0D U+0A U+1F1EF U+1F1F5
93. U+61: ʮaʯ U+0A U+1F146 U+200D U+1F692 U+0D จࣈ ͺ a \r \n & Unicode
 Scalar U+306F U+309A U+61 U+0D U+0A U+1F1EF U+1F1F5
94. U+61: ʮaʯ U+0A U+1F146 U+200D U+1F692 U+0D จࣈ ͺ a \r \n & Unicode
 Scalar U+306F U+309A U+61 U+0D U+0A U+1F1EF U+1F1F5
95. U+61: ʮaʯ U+0A U+1F146 U+200D U+1F692 U+0D: Carriage Return จࣈ ͺ a \r \n & Unicode
 Scalar U+306F U+309A U+61 U+0D U+0A U+1F1EF U+1F1F5
96. U+61: ʮaʯ U+0A U+1F146 U+200D U+1F692 U+0D: Carriage Return จࣈ ͺ a \r \n & Unicode
 Scalar U+306F U+309A U+61 U+0D U+0A U+1F1EF U+1F1F5 a
97. U+0A U+1F146 U+200D U+1F692 U+0D: Carriage Return จࣈ ͺ a \r \n & Unicode
 Scalar U+306F U+309A U+61 U+0D U+0A U+1F1EF U+1F1F5
98. U+1F146 U+200D U+1F692 U+0D: Carriage Return U+0A จࣈ ͺ a \r \n & Unicode
 Scalar U+306F U+309A U+61 U+0D U+0A U+1F1EF U+1F1F5
99. U+1F146 U+200D U+1F692 U+0D: Carriage Return U+0A จࣈ ͺ a \r \n & Unicode
 Scalar U+306F U+309A U+61 U+0D U+0A U+1F1EF U+1F1F5
100. U+1F146 U+200D U+1F692 U+0D: Carriage Return U+0A: Line Feed จࣈ ͺ a \r \n & Unicode
 Scalar U+306F U+309A U+61 U+0D U+0A U+1F1EF U+1F1F5
101. U+1F146 U+200D U+1F692 U+0D: Carriage Return U+0A: Line Feed จࣈ ͺ a \r \n & Unicode
 Scalar U+306F U+309A U+61 U+0D U+0A U+1F1EF U+1F1F5 \r\n ͷ૊Έ߹Θͤ͸ ಛผѻ͍
102. U+1F146 U+200D U+1F692 จࣈ ͺ a \r \n & Unicode
 Scalar U+306F U+309A U+61 U+0D U+0A U+1F1EF U+1F1F5
103. U+200D U+1F692 U+1F1EF จࣈ ͺ a \r \n & Unicode
 Scalar U+306F U+309A U+61 U+0D U+0A U+1F1EF U+1F1F5
104. U+200D U+1F692 U+1F1EF จࣈ ͺ a \r \n & Unicode
 Scalar U+306F U+309A U+61 U+0D U+0A U+1F1EF U+1F1F5
105. U+200D U+1F692 U+1F1EF: จࣈ ͺ a \r \n & Unicode
 Scalar U+306F U+309A U+61 U+0D U+0A U+1F1EF U+1F1F5 J
106. U+200D U+1F692 U+1F1EF: จࣈ ͺ a \r \n & Unicode
 Scalar U+306F U+309A U+61 U+0D U+0A U+1F1EF U+1F1F5 ࠃίʔυͷʮJʯ J
107. U+200D U+1F1EF: U+1F1F5 จࣈ ͺ a \r \n & Unicode
 Scalar U+306F U+309A U+61 U+0D U+0A U+1F1EF U+1F1F5 J
108. U+200D U+1F1EF: U+1F1F5 จࣈ ͺ a \r \n & Unicode
 Scalar U+306F U+309A U+61 U+0D U+0A U+1F1EF U+1F1F5 J
109. U+200D U+1F1EF: U+1F1F5: จࣈ ͺ a \r \n & Unicode
 Scalar U+306F U+309A U+61 U+0D U+0A U+1F1EF U+1F1F5 J P
110. U+200D U+1F1EF: U+1F1F5: จࣈ ͺ a \r \n & Unicode
 Scalar U+306F U+309A U+61 U+0D U+0A U+1F1EF U+1F1F5 J P ࠃίʔυʮJʯ+ʮPʯ Ͱ೔ຊ
111. U+200D จࣈ ͺ a \r \n & Unicode
 Scalar U+306F U+309A U+61 U+0D U+0A U+1F1EF U+1F1F5
112. U+200D จࣈ ͺ a \r \n & Unicode
 Scalar U+306F U+309A U+61 U+0D U+0A U+1F1EF U+1F1F5 1 2 3 4
113. U+200D จࣈ ͺ a \r \n & Unicode
 Scalar U+306F U+309A U+61 U+0D U+0A U+1F1EF U+1F1F5 1 2 3 4 ΋͠\nͰ͸ͳͯ͘ʮbʯ ͩͬͨΒ
114. U+200D จࣈ ͺ a \r b & Unicode
 Scalar U+306F U+309A U+61 U+0D U+62 U+1F1EF U+1F1F5 1 2 3 4
115. U+200D จࣈ ͺ a \r b & Unicode
 Scalar U+306F U+309A U+61 U+0D U+62 U+1F1EF U+1F1F5 1 2 3 4 \r ͱ b ͸݁߹͠ͳ͍
116. U+200D จࣈ ͺ a \r b & Unicode
 Scalar U+306F U+309A U+61 U+0D U+62 U+1F1EF U+1F1F5 1 2 3 4 5
117. U+200D จࣈ ͺ a \r b & Unicode
 Scalar U+306F U+309A U+61 U+0D U+62 U+1F1EF U+1F1F5 1 2 3 4 5 4จࣈ໨ͩͬͨ΋ͷ͕ 5จࣈ໨ʹ
118. U+200D จࣈ ͺ a \r b & Unicode
 Scalar U+306F U+309A U+61 U+0D U+62 U+1F1EF U+1F1F5 1 2 3 4 5 N൪໨ͷจࣈΛ஌ΔͨΊʹ͸ɺ ͦͷલʹ͋ΔจࣈΛ஌Δඞཁ͕͋Δɻ
119. U+200D จࣈ ͺ a \r b & Unicode
 Scalar U+306F U+309A U+61 U+0D U+62 U+1F1EF U+1F1F5 1 2 3 4 5 N൪໨ͷจࣈΛ஌ΔͨΊʹ͸ɺ ͦͷલʹ͋ΔจࣈΛ஌Δඞཁ͕͋Δɻ ‑ N൪໨ͷจࣈΛऔಘ͢ΔͨΊͷܭࢉྔ͸O(N)
120. U+200D จࣈ ͺ a \r b & Unicode
 Scalar U+306F U+309A U+61 U+0D U+62 U+1F1EF U+1F1F5 1 2 3 4 5 N൪໨ͷจࣈΛ஌ΔͨΊʹ͸ɺ ͦͷલʹ͋ΔจࣈΛ஌Δඞཁ͕͋Δɻ ‑ N൪໨ͷจࣈΛऔಘ͢ΔͨΊͷܭࢉྔ͸ O(N)
121. ܭࢉྔ ܭࢉʹ͔͔Δ࣌ؒ จࣈͷҐஔ
122. ܭࢉྔ ܭࢉʹ͔͔Δ࣌ؒ จࣈͷҐஔ O(N)
123. String͸Collectionʹ४ڌ • ఴࣈΞΫηεͷܭࢉྔ͸O(1)Ͱͳ͍ͱ͍͚ͳ͍
124. ܭࢉྔ ܭࢉʹ͔͔Δ࣌ؒ จࣈͷҐஔ O(N)
125. ܭࢉྔ ܭࢉʹ͔͔Δ࣌ؒ จࣈͷҐஔ O(N) Collectionϓϩτίϧͷ ཁ੥
126. ܭࢉྔ ܭࢉʹ͔͔Δ࣌ؒ จࣈͷҐஔ IntͰఴࣈΞΫηεͨ͠ͱ͖ʹ͔ ͔Δ࣌ؒ O(N) Collectionϓϩτίϧͷ ཁ੥ O(1)
127. ܭࢉྔ ܭࢉʹ͔͔Δ࣌ؒ จࣈͷҐஔ IntͰఴࣈΞΫηεͨ͠ͱ͖ʹ͔ ͔Δ࣌ؒ O(N) Collectionϓϩτίϧͷ ཁ੥ O(1) String͸IntͰ͸ఴࣈΞΫηε Ͱ͖ͳ͍
128. StringͷఴࣈΞΫηεʹ͍ͭͯ
129. String.Index StringͷఴࣈΞΫηεʹ͍ͭͯ
130. String.Index StringͷఴࣈΞΫηεʹ͍ͭͯ ࢝఺͔ΒͷΦϑηοτ
131. ΞδΣϯμ - SwiftͷStringʹ͍ͭͯ - Unicodeʹ͍ͭͯ -Stringͱཁૉͷஔ͖׵͑ʹ͍ͭͯ
132. ཁૉͷஔ͖׵͕͑Ͱ͖ͳ͍
133. Array String " #
134. Array String " # ఴࣈΞΫηεͰsetͰ͖Δ ఴࣈΞΫηεͰsetͰ͖ͳ͍
135. Array String " # ఴࣈΞΫηεͰsetͰ͖Δ ఴࣈΞΫηεͰsetͰ͖ͳ͍ MutableCollectionʹ४ڌ͍ͯ͠Δ MutableCollectionʹ४ڌ͍ͯ͠ͳ͍
136. Array String " # ఴࣈΞΫηεͰsetͰ͖Δ ఴࣈΞΫηεͰsetͰ͖ͳ͍ MutableCollectionʹ४ڌ͍ͯ͠Δ MutableCollectionʹ४ڌ͍ͯ͠ͳ͍
137. Sequence Collection MutableCollection
138. Sequence Collection MutableCollection - ఴࣈΞΫηεʹΑΔgetΛ ఆٛ - ఴࣈΞΫηεʹΑΔsetΛ ఆٛ
139. Sequence Collection MutableCollection - ఴࣈΞΫηεʹΑΔgetΛ ఆٛ - ఴࣈΞΫηεʹΑΔsetΛ ఆٛ ܭࢉྔ͸O(1) ͲͪΒ΋ܭࢉྔ͸O(1)
140. Sequence Collection MutableCollection String Sequence Collection MutableCollection Array
141. Sequence Collection MutableCollection String Sequence Collection MutableCollection Array ఴࣈΞΫηεʹΑΔset ͕O(1)Ͱ࣮ݱͰ͖ͳ͍͔Β
142. จࣈ ͏ a b c Unicode
 Scalar U+3046 U+61 U+62 U+63 var string = “͏abc" string[string.startIndex] = "X"
143. จࣈ ͏ a b c Unicode
 Scalar U+3046 U+61 U+62 U+63 var string = “͏abc" string[string.startIndex] = "X"
144. จࣈ X a b c Unicode
 Scalar U+58 U+61 U+62 U+63 var string = “͏abc" string[string.startIndex] = "X"
145. จࣈ ͏ a b c Unicode
 Scalar U+3046 U+61 U+62 U+63 จࣈ X a b c Unicode
 Scalar U+58 U+61 U+62 U+63
146. จࣈ ͏ a b c Unicode
 Scalar U+3046 U+61 U+62 U+63 UTF-8 E3 81 85 61 62 63 จࣈ X a b c Unicode
 Scalar U+58 U+61 U+62 U+63 UTF-8 58 61 62 63
147. จࣈ ͏ a b c Unicode
 Scalar U+3046 U+61 U+62 U+63 UTF-8 E3 81 85 61 62 63 จࣈ X a b c Unicode
 Scalar U+58 U+61 U+62 U+63 UTF-8 58 61 62 63
148. จࣈ ͏ a b c Unicode
 Scalar U+3046 U+61 U+62 U+63 UTF-8 E3 81 85 61 62 63 όΠτ෯ 3 1 1 1 จࣈ X a b c Unicode
 Scalar U+58 U+61 U+62 U+63 UTF-8 58 61 62 63 όΠυ෯ 1 1 1 1
150. 1όΠτ
151. a b c ͏
152. a b c ͏ a b c X
153. a b c ͏ a b c X
154. a c b ͏ b c a X ೖΕସ͑ͨจࣈͷҎ߱ͷจࣈͷόΠτྻΛҠಈ͢Δඞཁ͕͋Δ ‑ ఴࣈΞΫηεʹΑΔ set ͷܭࢉྔ͸O(N)
155. ·ͱΊ - ҰͭͷCharacterͷ಺෦දݱ͕ͦΕͧΕҟͳΔͷͰɺ CharacterͷऔಘͱೖΕସ͑ͷܭࢉྔ͕O(1)ʹͳΒͳ͍ - IntͰఴࣈΞΫηεͰ͖ͳ͍ - MutableCollectionʹ४ڌ͠ͳ͍