iOS-GCD和强参考_Ios_Objective C_Multithreading_Objective C Blocks

iOS-GCD和强参考

ios objective-c multithreading

iOS-GCD和强参考,ios,objective-c,multithreading,objective-c-blocks,Ios,Objective C,Multithreading,Objective C Blocks,我有这段代码，我试图做的是让self在块中保持活动状态，它将在主线程上执行。结果是随机的，有时打印为空 - (void)viewDidLoad { [super viewDidLoad]; // Do any additional setup after loading the view. self.proArray = [[NSMutableArray alloc]init]; GCDVC2* __weak weakSelf = self; self

我有这段代码，我试图做的是让self在块中保持活动状态，它将在主线程上执行。结果是随机的，有时打印为空

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view.
    self.proArray = [[NSMutableArray alloc]init];

    GCDVC2* __weak weakSelf = self;

    self.postGCDBlock = ^{

        GCDVC2* __strong strongSelf2 = weakSelf;

        [strongSelf2.proArray removeObject:@"3"];
        NSLog(@"%@",strongSelf2.proArray);
        [strongSelf2.activityIndicator stopAnimating];
    };

    self.addObjectsBlock = ^{

        GCDVC2* __strong strongSelf = weakSelf;

        [strongSelf.proArray addObject:@"2"];
        [strongSelf.proArray addObject:@"3"];
        [NSThread sleepForTimeInterval:5];

        dispatch_async(dispatch_get_main_queue(),strongSelf.postGCDBlock);
    };

    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0), self.addObjectsBlock);

}

此代码工作正常：

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view.
    self.proArray = [[NSMutableArray alloc]init];

    GCDVC2* __weak weakSelf = self;


    //self.postGCDBlock = ;

    self.addObjectsBlock = ^{

        GCDVC2* __strong strongSelf = weakSelf;

        [strongSelf.proArray addObject:@"2"];
        [strongSelf.proArray addObject:@"3"];
        [NSThread sleepForTimeInterval:5];

         GCDVC2* __weak weakSelf2 = strongSelf;

        dispatch_async(dispatch_get_main_queue(),^{

            GCDVC2* __strong strongSelf = weakSelf2;

            [strongSelf.proArray removeObject:@"3"];
            NSLog(@"%@",strongSelf.proArray);
            [strongSelf.activityIndicator stopAnimating];
        });
    };

    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0), self.addObjectsBlock);

}

有没有办法将第二段代码转换为第一段代码的结构？我尝试了很多变化，但总是随机的。我能保证self.postGCDBlock不会有self-to-nil吗

更新：财产申报：

typedef void(^CustomBlock)(void);

@interface GCDVC2 ()
@property (weak, nonatomic) IBOutlet UIActivityIndicatorView *activityIndicator;
@property(nonatomic,strong)NSMutableArray *proArray;
@property (nonatomic, copy) CustomBlock addObjectsBlock;
@property (nonatomic, copy) CustomBlock postGCDBlock;
@end

我认为您的问题在于这一行（我无法用此代码再现故障案例）：

此时，在

addObjectsBlock

中，

strongSelf

包含对

self

的引用，但当您离开该块的范围时，该引用即告结束

dispatch\u async

将复制

postGCDBlock

，但该块不包含对

self

的强引用

要获得

dispatch\u async

以保存对

self

的强引用，您需要执行以下操作：

dispatch_async(dispatch_get_main_queue(), ^{
    strongSelf.postGCDBlock();
});

在块中包装

strongSelf

将导致

dispatch\u async

保留

strongSelf

（从而

self

）足够长的时间，以便调用

postGCDBlock

，我认为您的问题在于这一行（我无法用此代码重现故障案例）：