你以为避免 block 循环引用只要 weakself就好了？

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Block 循环引用怎么处理？只要把Block里面的self改成weakSelf就好了吗？navie了大兄弟。

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@interface RenderEngine:NSObject

- property (nonatomic, copy) (void (^)(OreoView *view)) finish;

@end

@implemtation RenderEngine
// ...
@end

@interface OreoView:UIView

@property (nonatomic, strong) RenderEngine *engine;

@end

@implemtation OreoView

- (void)dealloc {
   [_engine destroy];
}

@end


@interface Oreo: NSObject
+ (void)getViewById:(NSString*)id finish:(void (^)(OreoView *view))finish;
@end
@implemtation Oreo

+ (void)getViewById:(NSString*)id finish:(void (^)(OreoView *view))finish {
   RenderEngine *engine = [RenderEngine new];
   engine.finish = finish;
   // 渲染Oreo视图
   // ...
   OreoView *view = ...;
   view.engine = engine;
   if (engine.finish) {
       engine.finish(view);
   }
}
@end

RenderEngine 是一个视图渲染引擎（Weex）， RenderEngine 会去渲染视图，渲染是一个异步操作，所以它会持有一个结束回调finish，渲染出来的这个视图会持有这个渲染引擎，在视图释放时释放引擎。假如你这么写finish回调，那么retain cycle就来了。

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Obj someObj = [Obj new];
[Oreo getViewById:@"123" finish:(OreoView *view) {
   someObj.view = view;
}];

即时VC被释放了，someObj也不会被释放。所以用block时只考虑self就够了吗。 😁
Block里面只要用到了外部对象都有可能引起 retain cycle。