objective-c - 关于Masonry为什么不会造成循环引用的问题

Question

代码举个例子，我不知道自己的理解对不对。

[self.view mas_makeConstraints:^(MASConstraintMaker *make) {
    make.centerY.equalTo(self.otherView.mas_centerY);
}];

block中持有了self，但是self.view并没有持有这个block，因为看到Masonry的源码是这样的：

- (NSArray *)mas_makeConstraints:(void(^)(MASConstraintMaker *))block {
    self.translatesAutoresizingMaskIntoConstraints = NO;
    MASConstraintMaker *constraintMaker = [[MASConstraintMaker alloc] initWithView:self];
    block(constraintMaker);
    return [constraintMaker install];
}

它仅仅是block(constrainMaker)。如果改成了self.block = block(constrainMaker)，那么view是不是也持有了block呢

Answer 1

It is not true that block will definitely cause a circular reference. Whether it is a circular reference depends on whether they hold strong references to each other. If self is used in a block, the block will keep a reference to self, but self does not hold the block directly or indirectly, so it will not cause a circular reference.

Your understanding is correct.