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FlutterSpellCheckPlugin.mm
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1 // Copyright 2013 The Flutter Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
4
5 #import "flutter/shell/platform/darwin/ios/framework/Source/FlutterSpellCheckPlugin.h"
6
7 #import <Foundation/Foundation.h>
8 #import <UIKit/UIKit.h>
9
10 #import "flutter/fml/logging.h"
11
12 FLUTTER_ASSERT_ARC
13
14 // Method Channel name to start spell check.
15 static NSString* const kInitiateSpellCheck = @"SpellCheck.initiateSpellCheck";
16
17 @interface FlutterSpellCheckResult : NSObject
18
19 @property(nonatomic, copy, readonly) NSArray<NSString*>* suggestions;
20 @property(nonatomic, assign, readonly) NSRange misspelledRange;
21
22 - (instancetype)init NS_UNAVAILABLE;
23 + (instancetype)new NS_UNAVAILABLE;
24 - (instancetype)initWithMisspelledRange:(NSRange)range
25 suggestions:(NSArray<NSString*>*)suggestions NS_DESIGNATED_INITIALIZER;
26 - (NSDictionary<NSString*, NSObject*>*)toDictionary;
27
28 @end
29
30 @interface FlutterSpellCheckPlugin ()
31
32 @property(nonatomic) UITextChecker* textChecker;
33
34 @end
35
36 @implementation FlutterSpellCheckPlugin
37
38 - (void)handleMethodCall:(FlutterMethodCall*)call result:(FlutterResult)result {
39 if (!self.textChecker) {
40 // UITextChecker is an expensive object to initiate, see:
41 // https://github.com/flutter/flutter/issues/104454. Lazily initialate the UITextChecker object
42 // until at first method channel call. We avoid using lazy getter for testing.
43 self.textChecker = [[UITextChecker alloc] init];
44 }
45 NSString* method = call.method;
46 NSArray* args = call.arguments;
47 if ([method isEqualToString:kInitiateSpellCheck]) {
48 FML_DCHECK(args.count == 2);
49 id language = args[0];
50 id text = args[1];
51 if (language == [NSNull null] || text == [NSNull null]) {
52 // Bail if null arguments are passed from dart.
53 result(nil);
54 return;
55 }
56
57 NSArray<NSDictionary<NSString*, id>*>* spellCheckResult =
58 [self findAllSpellCheckSuggestionsForText:text inLanguage:language];
59 result(spellCheckResult);
60 }
61 }
62
63 // Get all the misspelled words and suggestions in the entire String.
64 //
65 // The result will be formatted as an NSArray.
66 // Each item of the array is a dictionary representing a misspelled word and suggestions.
67 // The format looks like:
68 // {
69 // startIndex: 0,
70 // endIndex: 5,
71 // suggestions: [hello, ...]
72 // }
73 //
74 // Returns nil if the language is invalid.
75 // Returns an empty array if no spell check suggestions.
76 - (NSArray<NSDictionary<NSString*, id>*>*)findAllSpellCheckSuggestionsForText:(NSString*)text
77 inLanguage:(NSString*)language {
78 // Transform Dart Locale format to iOS language format if necessary.
79 if ([language containsString:@"-"]) {
80 NSArray<NSString*>* languageCodes = [language componentsSeparatedByString:@"-"];
81 FML_DCHECK(languageCodes.count == 2);
82 NSString* lastCode = [[languageCodes lastObject] uppercaseString];
83 language = [NSString stringWithFormat:@"%@_%@", [languageCodes firstObject], lastCode];
84 }
85
86 if (![UITextChecker.availableLanguages containsObject:language]) {
87 return nil;
88 }
89
90 NSMutableArray<FlutterSpellCheckResult*>* allSpellSuggestions = [[NSMutableArray alloc] init];
91
92 FlutterSpellCheckResult* nextSpellSuggestion;
93 NSUInteger nextOffset = 0;
94 do {
95 nextSpellSuggestion = [self findSpellCheckSuggestionsForText:text
96 inLanguage:language
97 startingOffset:nextOffset];
98 if (nextSpellSuggestion != nil) {
99 [allSpellSuggestions addObject:nextSpellSuggestion];
100 nextOffset =
101 nextSpellSuggestion.misspelledRange.location + nextSpellSuggestion.misspelledRange.length;
102 }
103 } while (nextSpellSuggestion != nil && nextOffset < text.length);
104
105 NSMutableArray* methodChannelResult =
106 [[NSMutableArray alloc] initWithCapacity:allSpellSuggestions.count];
107
108 for (FlutterSpellCheckResult* result in allSpellSuggestions) {
109 [methodChannelResult addObject:[result toDictionary]];
110 }
111
112 return methodChannelResult;
113 }
114
115 // Get the misspelled word and suggestions.
116 //
117 // Returns nil if no spell check suggestions.
118 - (FlutterSpellCheckResult*)findSpellCheckSuggestionsForText:(NSString*)text
119 inLanguage:(NSString*)language
120 startingOffset:(NSInteger)startingOffset {
121 FML_DCHECK([UITextChecker.availableLanguages containsObject:language]);
122 NSRange misspelledRange =
123 [self.textChecker rangeOfMisspelledWordInString:text
124 range:NSMakeRange(0, text.length)
125 startingAt:startingOffset
126 wrap:NO
127 language:language];
128 if (misspelledRange.location == NSNotFound) {
129 // No misspelled word found
130 return nil;
131 }
132
133 // If no possible guesses, the API returns an empty array:
134 // https://developer.apple.com/documentation/uikit/uitextchecker/1621037-guessesforwordrange?language=objc
135 NSArray<NSString*>* suggestions = [self.textChecker guessesForWordRange:misspelledRange
136 inString:text
137 language:language];
138 return [[FlutterSpellCheckResult alloc] initWithMisspelledRange:misspelledRange
139 suggestions:suggestions];
140 }
141
142 @end
143
144 @implementation FlutterSpellCheckResult
145
146 - (instancetype)initWithMisspelledRange:(NSRange)range
147 suggestions:(NSArray<NSString*>*)suggestions {
148 self = [super init];
149 if (self) {
150 _suggestions = [suggestions copy];
151 _misspelledRange = range;
152 }
153 return self;
154 }
155
156 - (NSDictionary<NSString*, NSObject*>*)toDictionary {
157 return @{
158 @"startIndex" : @(_misspelledRange.location),
159 // The end index represents the next index after the last character of a misspelled word to
160 // match the behavior of Dart's TextRange:
161 // https://api.flutter.dev/flutter/dart-ui/TextRange/end.html
162 @"endIndex" : @(_misspelledRange.location + _misspelledRange.length),
163 @"suggestions" : _suggestions,
164 };
165 }
166
167 @end
FlutterResult
void(^ FlutterResult)(id _Nullable result)
Definition: FlutterChannels.h:194
FlutterSpellCheckPlugin.h
kInitiateSpellCheck
static FLUTTER_ASSERT_ARC NSString *const kInitiateSpellCheck
Definition: FlutterSpellCheckPlugin.mm:15
FlutterMethodCall
Definition: FlutterCodecs.h:221
FlutterMethodCall::method
NSString * method
Definition: FlutterCodecs.h:233
FlutterMethodCall::arguments
id arguments
Definition: FlutterCodecs.h:238
FlutterSpellCheckPlugin
Definition: FlutterSpellCheckPlugin.h:12
FlutterSpellCheckResult
Definition: FlutterSpellCheckPlugin.mm:18
FlutterSpellCheckResult::misspelledRange
NSRange misspelledRange
Definition: FlutterSpellCheckPlugin.mm:20
FlutterSpellCheckResult::suggestions
NSArray< NSString * > * suggestions
Definition: FlutterSpellCheckPlugin.mm:19
-[FlutterSpellCheckResult NS_UNAVAILABLE]
instancetype NS_UNAVAILABLE()
-[FlutterSpellCheckResult toDictionary]
NSDictionary< NSString *, NSObject * > * toDictionary()
Definition: FlutterSpellCheckPlugin.mm:156
FLUTTER_ASSERT_ARC
Definition: FlutterChannelKeyResponder.mm:13