Block循环引用问题

IOS中block循环引用现象:
例如:

block循环引用.png

判断方法:

//调用了dealloc方法就说明self被释放了,否则说明self在block里被循环引用了
-(void)dealloc
{
    NSLog(@"%s",__func__);
}

解决方法:

//弱引用self
__weak typeof(self) weakself = self;
item.operation = ^ {
   ...
   [weakself presentViewController:... animated:... completion:...];
   ...
}