Flutter iOS Embedder
FlutterEngine.h
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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 #ifndef FLUTTER_FLUTTERENGINE_H_
6 #define FLUTTER_FLUTTERENGINE_H_
7 
8 #import <Foundation/Foundation.h>
9 #import <UIKit/UIKit.h>
10 
12 #import "FlutterDartProject.h"
13 #import "FlutterMacros.h"
14 #import "FlutterPlugin.h"
15 #import "FlutterTexture.h"
16 
18 
20 
21 /**
22  * The dart entrypoint that is associated with `main()`. This is to be used as an argument to the
23  * `runWithEntrypoint*` methods.
24  */
25 extern NSString* const FlutterDefaultDartEntrypoint;
26 
27 /**
28  * The default Flutter initial route ("/").
29  */
30 extern NSString* const FlutterDefaultInitialRoute;
31 
32 /**
33  * The FlutterEngine class coordinates a single instance of execution for a
34  * `FlutterDartProject`. It may have zero or one `FlutterViewController` at a
35  * time, which can be specified via `-setViewController:`.
36  * `FlutterViewController`'s `initWithEngine` initializer will automatically call
37  * `-setViewController:` for itself.
38  *
39  * A FlutterEngine can be created independently of a `FlutterViewController` for
40  * headless execution. It can also persist across the lifespan of multiple
41  * `FlutterViewController` instances to maintain state and/or asynchronous tasks
42  * (such as downloading a large file).
43  *
44  * A FlutterEngine can also be used to prewarm the Dart execution environment and reduce the
45  * latency of showing the Flutter screen when a `FlutterViewController` is created and presented.
46  * See http://flutter.dev/docs/development/add-to-app/performance for more details on loading
47  * performance.
48  *
49  * Alternatively, you can simply create a new `FlutterViewController` with only a
50  * `FlutterDartProject`. That `FlutterViewController` will internally manage its
51  * own instance of a FlutterEngine, but will not guarantee survival of the engine
52  * beyond the life of the ViewController.
53  *
54  * A newly initialized FlutterEngine will not actually run a Dart Isolate until
55  * either `-runWithEntrypoint:` or `-runWithEntrypoint:libraryURI` is invoked.
56  * One of these methods must be invoked before calling `-setViewController:`.
57  */
59 @interface FlutterEngine : NSObject <FlutterPluginRegistry>
60 
61 /**
62  * Default initializer for a FlutterEngine.
63  *
64  * Threads created by this FlutterEngine will appear as "FlutterEngine #" in
65  * Instruments. The prefix can be customized using `initWithName`.
66  *
67  * The engine will execute the project located in the bundle with the identifier
68  * "io.flutter.flutter.app" (the default for Flutter projects).
69  *
70  * A newly initialized engine will not run until either `-runWithEntrypoint:` or
71  * `-runWithEntrypoint:libraryURI:` is called.
72  *
73  * FlutterEngine created with this method will have allowHeadlessExecution set to `YES`.
74  * This means that the engine will continue to run regardless of whether a `FlutterViewController`
75  * is attached to it or not, until `-destroyContext:` is called or the process finishes.
76  */
77 - (instancetype)init;
78 
79 /**
80  * Initialize this FlutterEngine.
81  *
82  * The engine will execute the project located in the bundle with the identifier
83  * "io.flutter.flutter.app" (the default for Flutter projects).
84  *
85  * A newly initialized engine will not run until either `-runWithEntrypoint:` or
86  * `-runWithEntrypoint:libraryURI:` is called.
87  *
88  * FlutterEngine created with this method will have allowHeadlessExecution set to `YES`.
89  * This means that the engine will continue to run regardless of whether a `FlutterViewController`
90  * is attached to it or not, until `-destroyContext:` is called or the process finishes.
91  *
92  * @param labelPrefix The label prefix used to identify threads for this instance. Should
93  * be unique across FlutterEngine instances, and is used in instrumentation to label
94  * the threads used by this FlutterEngine.
95  */
96 - (instancetype)initWithName:(NSString*)labelPrefix;
97 
98 /**
99  * Initialize this FlutterEngine with a `FlutterDartProject`.
100  *
101  * If the FlutterDartProject is not specified, the FlutterEngine will attempt to locate
102  * the project in a default location (the flutter_assets folder in the iOS application
103  * bundle).
104  *
105  * A newly initialized engine will not run the `FlutterDartProject` until either
106  * `-runWithEntrypoint:` or `-runWithEntrypoint:libraryURI:` is called.
107  *
108  * FlutterEngine created with this method will have allowHeadlessExecution set to `YES`.
109  * This means that the engine will continue to run regardless of whether a `FlutterViewController`
110  * is attached to it or not, until `-destroyContext:` is called or the process finishes.
111  *
112  * @param labelPrefix The label prefix used to identify threads for this instance. Should
113  * be unique across FlutterEngine instances, and is used in instrumentation to label
114  * the threads used by this FlutterEngine.
115  * @param project The `FlutterDartProject` to run.
116  */
117 - (instancetype)initWithName:(NSString*)labelPrefix project:(nullable FlutterDartProject*)project;
118 
119 /**
120  * Initialize this FlutterEngine with a `FlutterDartProject`.
121  *
122  * If the FlutterDartProject is not specified, the FlutterEngine will attempt to locate
123  * the project in a default location (the flutter_assets folder in the iOS application
124  * bundle).
125  *
126  * A newly initialized engine will not run the `FlutterDartProject` until either
127  * `-runWithEntrypoint:` or `-runWithEntrypoint:libraryURI:` is called.
128  *
129  * @param labelPrefix The label prefix used to identify threads for this instance. Should
130  * be unique across FlutterEngine instances, and is used in instrumentation to label
131  * the threads used by this FlutterEngine.
132  * @param project The `FlutterDartProject` to run.
133  * @param allowHeadlessExecution Whether or not to allow this instance to continue
134  * running after passing a nil `FlutterViewController` to `-setViewController:`.
135  */
136 - (instancetype)initWithName:(NSString*)labelPrefix
137  project:(nullable FlutterDartProject*)project
138  allowHeadlessExecution:(BOOL)allowHeadlessExecution;
139 
140 /**
141  * Initialize this FlutterEngine with a `FlutterDartProject`.
142  *
143  * If the FlutterDartProject is not specified, the FlutterEngine will attempt to locate
144  * the project in a default location (the flutter_assets folder in the iOS application
145  * bundle).
146  *
147  * A newly initialized engine will not run the `FlutterDartProject` until either
148  * `-runWithEntrypoint:` or `-runWithEntrypoint:libraryURI:` is called.
149  *
150  * @param labelPrefix The label prefix used to identify threads for this instance. Should
151  * be unique across FlutterEngine instances, and is used in instrumentation to label
152  * the threads used by this FlutterEngine.
153  * @param project The `FlutterDartProject` to run.
154  * @param allowHeadlessExecution Whether or not to allow this instance to continue
155  * running after passing a nil `FlutterViewController` to `-setViewController:`.
156  * @param restorationEnabled Whether state restoration is enabled. When true, the framework will
157  * wait for the attached view controller to provide restoration data.
158  */
159 - (instancetype)initWithName:(NSString*)labelPrefix
160  project:(nullable FlutterDartProject*)project
161  allowHeadlessExecution:(BOOL)allowHeadlessExecution
162  restorationEnabled:(BOOL)restorationEnabled NS_DESIGNATED_INITIALIZER;
163 
164 /**
165  * Runs a Dart program on an Isolate from the main Dart library (i.e. the library that
166  * contains `main()`), using `main()` as the entrypoint (the default for Flutter projects),
167  * and using "/" (the default route) as the initial route.
168  *
169  * The first call to this method will create a new Isolate. Subsequent calls will return
170  * immediately and have no effect.
171  *
172  * @return YES if the call succeeds in creating and running a Flutter Engine instance; NO otherwise.
173  */
174 - (BOOL)run;
175 
176 /**
177  * Runs a Dart program on an Isolate from the main Dart library (i.e. the library that
178  * contains `main()`), using "/" (the default route) as the initial route.
179  *
180  * The first call to this method will create a new Isolate. Subsequent calls will return
181  * immediately and have no effect.
182  *
183  * @param entrypoint The name of a top-level function from the same Dart
184  * library that contains the app's main() function. If this is FlutterDefaultDartEntrypoint (or
185  * nil) it will default to `main()`. If it is not the app's main() function, that function must
186  * be decorated with `@pragma(vm:entry-point)` to ensure the method is not tree-shaken by the Dart
187  * compiler.
188  * @return YES if the call succeeds in creating and running a Flutter Engine instance; NO otherwise.
189  */
190 - (BOOL)runWithEntrypoint:(nullable NSString*)entrypoint;
191 
192 /**
193  * Runs a Dart program on an Isolate from the main Dart library (i.e. the library that
194  * contains `main()`).
195  *
196  * The first call to this method will create a new Isolate. Subsequent calls will return
197  * immediately and have no effect.
198  *
199  * @param entrypoint The name of a top-level function from the same Dart
200  * library that contains the app's main() function. If this is FlutterDefaultDartEntrypoint (or
201  * nil), it will default to `main()`. If it is not the app's main() function, that function must
202  * be decorated with `@pragma(vm:entry-point)` to ensure the method is not tree-shaken by the Dart
203  * compiler.
204  * @param initialRoute The name of the initial Flutter `Navigator` `Route` to load. If this is
205  * FlutterDefaultInitialRoute (or nil), it will default to the "/" route.
206  * @return YES if the call succeeds in creating and running a Flutter Engine instance; NO otherwise.
207  */
208 - (BOOL)runWithEntrypoint:(nullable NSString*)entrypoint
209  initialRoute:(nullable NSString*)initialRoute;
210 
211 /**
212  * Runs a Dart program on an Isolate using the specified entrypoint and Dart library,
213  * which may not be the same as the library containing the Dart program's `main()` function.
214  *
215  * The first call to this method will create a new Isolate. Subsequent calls will return
216  * immediately and have no effect.
217  *
218  * @param entrypoint The name of a top-level function from a Dart library. If this is
219  * FlutterDefaultDartEntrypoint (or nil); this will default to `main()`. If it is not the app's
220  * main() function, that function must be decorated with `@pragma(vm:entry-point)` to ensure the
221  * method is not tree-shaken by the Dart compiler.
222  * @param uri The URI of the Dart library which contains the entrypoint method
223  * (example "package:foo_package/main.dart"). If nil, this will default to
224  * the same library as the `main()` function in the Dart program.
225  * @return YES if the call succeeds in creating and running a Flutter Engine instance; NO otherwise.
226  */
227 - (BOOL)runWithEntrypoint:(nullable NSString*)entrypoint libraryURI:(nullable NSString*)uri;
228 
229 /**
230  * Runs a Dart program on an Isolate using the specified entrypoint and Dart library,
231  * which may not be the same as the library containing the Dart program's `main()` function.
232  *
233  * The first call to this method will create a new Isolate. Subsequent calls will return
234  * immediately and have no effect.
235  *
236  * @param entrypoint The name of a top-level function from a Dart library. If this is
237  * FlutterDefaultDartEntrypoint (or nil); this will default to `main()`. If it is not the app's
238  * main() function, that function must be decorated with `@pragma(vm:entry-point)` to ensure the
239  * method is not tree-shaken by the Dart compiler.
240  * @param libraryURI The URI of the Dart library which contains the entrypoint
241  * method (example "package:foo_package/main.dart"). If nil, this will
242  * default to the same library as the `main()` function in the Dart program.
243  * @param initialRoute The name of the initial Flutter `Navigator` `Route` to load. If this is
244  * FlutterDefaultInitialRoute (or nil), it will default to the "/" route.
245  * @return YES if the call succeeds in creating and running a Flutter Engine instance; NO otherwise.
246  */
247 - (BOOL)runWithEntrypoint:(nullable NSString*)entrypoint
248  libraryURI:(nullable NSString*)libraryURI
249  initialRoute:(nullable NSString*)initialRoute;
250 
251 /**
252  * Runs a Dart program on an Isolate using the specified entrypoint and Dart library,
253  * which may not be the same as the library containing the Dart program's `main()` function.
254  *
255  * The first call to this method will create a new Isolate. Subsequent calls will return
256  * immediately and have no effect.
257  *
258  * @param entrypoint The name of a top-level function from a Dart library. If this is
259  * FlutterDefaultDartEntrypoint (or nil); this will default to `main()`. If it is not the app's
260  * main() function, that function must be decorated with `@pragma(vm:entry-point)` to ensure the
261  * method is not tree-shaken by the Dart compiler.
262  * @param libraryURI The URI of the Dart library which contains the entrypoint
263  * method (example "package:foo_package/main.dart"). If nil, this will
264  * default to the same library as the `main()` function in the Dart program.
265  * @param initialRoute The name of the initial Flutter `Navigator` `Route` to load. If this is
266  * FlutterDefaultInitialRoute (or nil), it will default to the "/" route.
267  * @param entrypointArgs Arguments passed as a list of string to Dart's entrypoint function.
268  * @return YES if the call succeeds in creating and running a Flutter Engine instance; NO otherwise.
269  */
270 - (BOOL)runWithEntrypoint:(nullable NSString*)entrypoint
271  libraryURI:(nullable NSString*)libraryURI
272  initialRoute:(nullable NSString*)initialRoute
273  entrypointArgs:(nullable NSArray<NSString*>*)entrypointArgs;
274 
275 /**
276  * Destroy running context for an engine.
277  *
278  * This method can be used to force the FlutterEngine object to release all resources.
279  * After sending this message, the object will be in an unusable state until it is deallocated.
280  * Accessing properties or sending messages to it will result in undefined behavior or runtime
281  * errors.
282  */
283 - (void)destroyContext;
284 
285 /**
286  * Ensures that Flutter will generate a semantics tree.
287  *
288  * This is enabled by default if certain accessibility services are turned on by
289  * the user, or when using a Simulator. This method allows a user to turn
290  * semantics on when they would not ordinarily be generated and the performance
291  * overhead is not a concern, e.g. for UI testing. Note that semantics should
292  * never be programmatically turned off, as it would potentially disable
293  * accessibility services an end user has requested.
294  *
295  * This method must only be called after launching the engine via
296  * `-runWithEntrypoint:` or `-runWithEntryPoint:libraryURI`.
297  *
298  * Although this method returns synchronously, it does not guarantee that a
299  * semantics tree is actually available when the method returns. It
300  * synchronously ensures that the next frame the Flutter framework creates will
301  * have a semantics tree.
302  *
303  * You can subscribe to semantics updates via `NSNotificationCenter` by adding
304  * an observer for the name `FlutterSemanticsUpdateNotification`. The `object`
305  * parameter will be the `FlutterViewController` associated with the semantics
306  * update. This will asynchronously fire after a semantics tree has actually
307  * built (which may be some time after the frame has been rendered).
308  */
309 - (void)ensureSemanticsEnabled;
310 
311 /**
312  * Sets the `FlutterViewController` for this instance. The FlutterEngine must be
313  * running (e.g. a successful call to `-runWithEntrypoint:` or `-runWithEntrypoint:libraryURI`)
314  * before calling this method. Callers may pass nil to remove the viewController
315  * and have the engine run headless in the current process.
316  *
317  * A FlutterEngine can only have one `FlutterViewController` at a time. If there is
318  * already a `FlutterViewController` associated with this instance, this method will replace
319  * the engine's current viewController with the newly specified one.
320  *
321  * Setting the viewController will signal the engine to start animations and drawing, and unsetting
322  * it will signal the engine to stop animations and drawing. However, neither will impact the state
323  * of the Dart program's execution.
324  */
325 @property(nonatomic, weak) FlutterViewController* viewController;
326 
327 /**
328  * The `FlutterMethodChannel` used for localization related platform messages, such as
329  * setting the locale.
330  *
331  * Can be nil after `destroyContext` is called.
332  */
333 @property(nonatomic, readonly, nullable) FlutterMethodChannel* localizationChannel;
334 /**
335  * The `FlutterMethodChannel` used for navigation related platform messages.
336  *
337  * Can be nil after `destroyContext` is called.
338  *
339  * @see [Navigation
340  * Channel](https://api.flutter.dev/flutter/services/SystemChannels/navigation-constant.html)
341  * @see [Navigator Widget](https://api.flutter.dev/flutter/widgets/Navigator-class.html)
342  */
343 @property(nonatomic, readonly) FlutterMethodChannel* navigationChannel;
344 
345 /**
346  * The `FlutterMethodChannel` used for restoration related platform messages.
347  *
348  * Can be nil after `destroyContext` is called.
349  *
350  * @see [Restoration
351  * Channel](https://api.flutter.dev/flutter/services/SystemChannels/restoration-constant.html)
352  */
353 @property(nonatomic, readonly) FlutterMethodChannel* restorationChannel;
354 
355 /**
356  * The `FlutterMethodChannel` used for core platform messages, such as
357  * information about the screen orientation.
358  *
359  * Can be nil after `destroyContext` is called.
360  */
361 @property(nonatomic, readonly) FlutterMethodChannel* platformChannel;
362 
363 /**
364  * The `FlutterMethodChannel` used to communicate text input events to the
365  * Dart Isolate.
366  *
367  * Can be nil after `destroyContext` is called.
368  *
369  * @see [Text Input
370  * Channel](https://api.flutter.dev/flutter/services/SystemChannels/textInput-constant.html)
371  */
372 @property(nonatomic, readonly) FlutterMethodChannel* textInputChannel;
373 
374 /**
375  * The `FlutterBasicMessageChannel` used to communicate app lifecycle events
376  * to the Dart Isolate.
377  *
378  * Can be nil after `destroyContext` is called.
379  *
380  * @see [Lifecycle
381  * Channel](https://api.flutter.dev/flutter/services/SystemChannels/lifecycle-constant.html)
382  */
383 @property(nonatomic, readonly) FlutterBasicMessageChannel* lifecycleChannel;
384 
385 /**
386  * The `FlutterBasicMessageChannel` used for communicating system events, such as
387  * memory pressure events.
388  *
389  * Can be nil after `destroyContext` is called.
390  *
391  * @see [System
392  * Channel](https://api.flutter.dev/flutter/services/SystemChannels/system-constant.html)
393  */
394 @property(nonatomic, readonly) FlutterBasicMessageChannel* systemChannel;
395 
396 /**
397  * The `FlutterBasicMessageChannel` used for communicating user settings such as
398  * clock format and text scale.
399  *
400  * Can be nil after `destroyContext` is called.
401  */
402 @property(nonatomic, readonly) FlutterBasicMessageChannel* settingsChannel;
403 
404 /**
405  * The `FlutterBasicMessageChannel` used for communicating key events
406  * from physical keyboards
407  *
408  * Can be nil after `destroyContext` is called.
409  */
410 @property(nonatomic, readonly) FlutterBasicMessageChannel* keyEventChannel;
411 
412 /**
413  * The depcreated `NSURL` of the Dart VM Service for the service isolate.
414  *
415  * This is only set in debug and profile runtime modes, and only after the
416  * Dart VM Service is ready. In release mode or before the Dart VM Service has
417  * started, it returns `nil`.
418  */
419 @property(nonatomic, readonly, nullable)
420  NSURL* observatoryUrl FLUTTER_DEPRECATED("Use vmServiceUrl instead");
421 
422 /**
423  * The `NSURL` of the Dart VM Service for the service isolate.
424  *
425  * This is only set in debug and profile runtime modes, and only after the
426  * Dart VM Service is ready. In release mode or before the Dart VM Service has
427  * started, it returns `nil`.
428  */
429 @property(nonatomic, readonly, nullable) NSURL* vmServiceUrl;
430 
431 /**
432  * The `FlutterBinaryMessenger` associated with this FlutterEngine (used for communicating with
433  * channels).
434  */
435 @property(nonatomic, readonly) NSObject<FlutterBinaryMessenger>* binaryMessenger;
436 
437 /**
438  * The `FlutterTextureRegistry` associated with this FlutterEngine (used to register textures).
439  */
440 @property(nonatomic, readonly) NSObject<FlutterTextureRegistry>* textureRegistry;
441 
442 /**
443  * The UI Isolate ID of the engine.
444  *
445  * This property will be nil if the engine is not running.
446  */
447 @property(nonatomic, readonly, copy, nullable) NSString* isolateId;
448 
449 /**
450  * Whether or not GPU calls are allowed.
451  *
452  * Typically this is set when the app is backgrounded and foregrounded.
453  */
454 @property(nonatomic, assign) BOOL isGpuDisabled;
455 
456 @end
457 
459 
460 #endif // FLUTTER_FLUTTERENGINE_H_
FlutterEngine::systemChannel
FlutterBasicMessageChannel * systemChannel
Definition: FlutterEngine.h:394
FlutterEngine::isGpuDisabled
BOOL isGpuDisabled
Definition: FlutterEngine.h:454
FlutterEngine
Definition: FlutterEngine.h:59
FlutterBasicMessageChannel
Definition: FlutterChannels.h:39
FlutterEngine::textInputChannel
FlutterMethodChannel * textInputChannel
Definition: FlutterEngine.h:372
FlutterViewController
Definition: FlutterViewController.h:55
FlutterMethodChannel
Definition: FlutterChannels.h:222
FlutterEngine::binaryMessenger
NSObject< FlutterBinaryMessenger > * binaryMessenger
Definition: FlutterEngine.h:435
FlutterEngine::restorationChannel
FlutterMethodChannel * restorationChannel
Definition: FlutterEngine.h:353
FlutterEngine::isolateId
NSString * isolateId
Definition: FlutterEngine.h:447
NS_ASSUME_NONNULL_END
#define NS_ASSUME_NONNULL_END
Definition: FlutterMacros.h:20
-[FlutterEngine ensureSemanticsEnabled]
void ensureSemanticsEnabled()
Definition: FlutterEngine.mm:420
FlutterEngine::platformChannel
FlutterMethodChannel * platformChannel
Definition: FlutterEngine.h:361
FlutterEngine::settingsChannel
FlutterBasicMessageChannel * settingsChannel
Definition: FlutterEngine.h:402
FlutterPluginRegistry-p
Definition: FlutterPlugin.h:400
-[FlutterEngine init]
instancetype init()
Definition: FlutterEngine.mm:159
FlutterTexture.h
NS_ASSUME_NONNULL_BEGIN
#define NS_ASSUME_NONNULL_BEGIN
Definition: FlutterMacros.h:19
FlutterMacros.h
FlutterEngine::lifecycleChannel
FlutterBasicMessageChannel * lifecycleChannel
Definition: FlutterEngine.h:383
FlutterEngine::keyEventChannel
FlutterBasicMessageChannel * keyEventChannel
Definition: FlutterEngine.h:410
FlutterPlugin.h
FlutterEngine::vmServiceUrl
NSURL * vmServiceUrl
Definition: FlutterEngine.h:429
viewController
FlutterViewController * viewController
Definition: FlutterTextInputPluginTest.mm:92
FLUTTER_DEPRECATED
#define FLUTTER_DEPRECATED(msg)
Definition: FlutterMacros.h:30
FlutterEngine::localizationChannel
FlutterMethodChannel * localizationChannel
Definition: FlutterEngine.h:333
FlutterDefaultInitialRoute
NSString *const FlutterDefaultInitialRoute
Definition: FlutterEngine.mm:80
FlutterEngine::textureRegistry
NSObject< FlutterTextureRegistry > * textureRegistry
Definition: FlutterEngine.h:440
FlutterBinaryMessenger.h
FlutterDartProject.h
FlutterDefaultDartEntrypoint
NS_ASSUME_NONNULL_BEGIN NSString *const FlutterDefaultDartEntrypoint
Definition: FlutterEngine.mm:79
-[FlutterEngine destroyContext]
void destroyContext()
Definition: FlutterEngine.mm:480
FLUTTER_DARWIN_EXPORT
#define FLUTTER_DARWIN_EXPORT
Definition: FlutterMacros.h:14
FlutterDartProject
Definition: FlutterDartProject.mm:262
-[FlutterEngine run]
BOOL run()
Definition: FlutterEngine.mm:938
FlutterEngine::navigationChannel
FlutterMethodChannel * navigationChannel
Definition: FlutterEngine.h:343