詳解flutter engine 那些沒被釋放的東西

/**
 * Destroy running context for an engine.
 *
 * This method can be used to force the FlutterEngine object to release all resources.
 * After sending this message, the object will be in an unusable state until it is deallocated.
 * Accessing properties or sending messages to it will result in undefined behavior or runtime
 * errors.
 */
- (void)destroyContext;

- (instancetype)initWithPlugin:(NSString*)pluginKey flutterEngine:(FlutterEngine*)flutterEngine {
 self = [super init];
 NSAssert(self, @"Super init cannot be nil");
 _pluginKey = pluginKey;// [pluginKey retain];
 _flutterEngine = flutterEngine;// [flutterEngine retain];
 return self;
}

@implementation FlutterJSONMessageCodec
+ (instancetype)sharedInstance {
 static id _sharedInstance = nil;
 if (!_sharedInstance) {
 _sharedInstance = [FlutterJSONMessageCodec new];
 }
 return _sharedInstance;
}

#import "FlutterTesterViewController.h"
#import <Flutter/Flutter.h>
#import "GeneratedPluginRegistrant.h" 
 
@interface FlutterTesterViewController ()
@property (nonatomic, weak) FlutterViewController * ctr;
@property (nonatomic, weak) FlutterEngine * engine;
@end

@implementation FlutterTesterViewController
- (void)viewDidLoad {
 [super viewDidLoad];
 
 float Y = 210;
 [self createButton:@"加載boundle資源" frame:CGRectMake(80.0, Y, 160.0, 40.0) action:@selector(handleBoundleResource )];
 
 Y += 40.0 + 10;
 [self createButton:@"autorelease" frame:CGRectMake(80.0, Y, 160.0, 40.0) action:@selector(handleAutoRelase)];
 
 NSArray * paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
 NSString * path = [[paths objectAtIndex:0] stringByAppendingPathComponent:@"flutter_assets"] ;
 NSLog(@"path: %@",path);
 
}

-(void)handleNetWorkResource:(UIButton *)button{
 
}

/**

* 加載boundle資源

*/
- (void)handleBoundleResource {
 
 FlutterDartProject * dart = [[FlutterDartProject alloc] init];
 FlutterEngine * engine = [[FlutterEngine alloc] initWithName:@"ios.dart.flutter"
               project:dart];
 [engine runWithEntrypoint:nil];
 FlutterViewController* flutterViewController = [[FlutterViewController alloc] initWithEngine:engine nibName:nil bundle:nil];
 [GeneratedPluginRegistrant registerWithRegistry:flutterViewController];
 [self addBackButton:flutterViewController];
  [flutterViewController setInitialRoute:@"route1"];
 [self presentViewController:flutterViewController animated:YES completion:nil];
 self.engine = engine;
}

-(void)handleAutoRelase{
 
  FlutterBasicMessageChannel* channel;
 FlutterEngine * engine;
 @autoreleasepool {
  FlutterViewController* flutterViewController =
  [[FlutterViewController alloc] init];
  channel = flutterViewController.engine.systemChannel;
  engine = flutterViewController.engine;
  NSLog(@"engine111:%@",engine);
 }
 NSLog(@"engine222:%@",engine);
 [channel sendMessage:@"Hello!"];
 [channel setMessageHandler:^(id _Nullable message, FlutterReply _Nonnull callback) { }];
}

-(void)addBackButton:(UIViewController *)flutterViewController{
 dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(2 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
  UIButton * btn = [UIButton buttonWithType:UIButtonTypeSystem];
  [btn setTitle:@"關(guān)閉" forState:UIControlStateNormal];
  btn.frame = CGRectMake(10, 100, 50, 30);
  [btn addTarget:self action:@selector(buttonTap:) forControlEvents:UIControlEventTouchUpInside];
  [flutterViewController.view addSubview:btn];
  self.ctr = flutterViewController;
 });
}

-(void)buttonTap:(id)sender{
// [self.navigationController popViewControllerAnimated:YES];
 
 __weak __typeof(self)weakSelf = self;
 [self.ctr dismissViewControllerAnimated:YES completion:^{
  
  [weakSelf.engine destroyContext];
 }];

}

- (void)didReceiveMemoryWarning {
 [super didReceiveMemoryWarning];
 // Dispose of any resources that can be recreated.
}



-(UIButton *)createButton:(NSString *)title frame:(CGRect)frame action:(SEL)selector{
 
 UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];
 [button addTarget:self
    action:selector
  forControlEvents:UIControlEventTouchUpInside];
 [button setTitle:title forState:UIControlStateNormal];
 UIColor * bgcolor = [UIColor colorWithRed:arc4random()%256/255. green:arc4random()%256/255. blue:arc4random()%256/255. alpha:1];
 [button setBackgroundColor:bgcolor];
 button.frame = frame;
 [self.view addSubview:button];
 return button;
}

@end