Do you also consider circular reference issues when using some of the system's block APIs, such as the block version of UIView?

• In some block APIs of the system, the block version of UIView is animated when it is written 不需要 ,但也有一些api 需要考虑
• The following use methods 不会 cause circular reference problems

[UIView animateWithDuration:duration animations:^{ [self.superview layoutIfNeeded]; }];[[NSOperationQueue mainQueue] addOperationWithBlock:^{ self.someProperty = xyz; }];[[NSNotificationCenter defaultCenter] addObserverForName:@"someNotification" object:nil queue:[NSOperationQueue mainQueue] usingBlock:^(NSNotification * notification) { self.someProperty = xyz; }];

• However, if some of the parameters in the method are member variables, you can cause circular references, such as GCD, Nsnotificationcenter calls should be careful, such as GCD internal if self is referenced, and the parameters of the GCD is a member variable, you have to consider the circular reference, for example:

  • GCD

    • parsing: self-->_operationsqueue-->block-->self forms a closed loop, resulting in a circular reference

       __weak __typeof__ (self) weakSelf = Span class= "Hljs-keyword" >self;dispatch_group_async (_operationsgroup, _operationsqueue, ^{[weakSelf doSomething];[ Weakself Dosomethingelse];}
       );

  • Nsnotificationcenter

    • Analysis: self-->_observer-->block-->self form a closed loop, resulting in circular references

    __weak __typeof__(self) weakSelf = self;_observer = [[NSNotificationCenter defaultCenter]addObserverForName:@"testKey"object:nilqueue:nilusingBlock:^(NSNotification *note){ [weakSelf dismissModalViewControllerAnimated:YES];}];

Do you also consider circular reference issues when using some of the system's block APIs, such as the block version of UIView?