设置`constraint.isActive = false`是否解除约束？

Question

说我要删除一个约束，传统上，我会做：

view.removeConstraint(constraint) 

然而，现在有用于安装/卸载限制新的isActive方法。

如果我做到以下几点：

constraint.isActive = false 

将它从内存中正确删除呢？

Answer 1

是，

constraint.isActive = false 

在做同样的事情：

viewThatOwnsConstraint.removeConstraint(constraint) 

因此，如果持有到约束的唯一的事情就是看，那么这将正确地从内存中删除。

---

这里的证明：

let view = UIView() 

weak var weakView: UIView? = nil 
autoreleasepool { 
    weakView = UIView() 
} 
assert(weakView == nil) 

// Traditional way of removing constraints ensures that the constraint is deallocated 

weak var weakConstraint: NSLayoutConstraint? = nil 
autoreleasepool { 
    weakConstraint = view.widthAnchor.constraint(equalToConstant: 10) 
} 
assert(weakConstraint == nil) // nothing is holding on to the constraint 

autoreleasepool { 
    weakConstraint = view.widthAnchor.constraint(equalToConstant: 10) 
    view.addConstraint(weakConstraint!) 
} 
assert(weakConstraint != nil) 

autoreleasepool { 
    view.removeConstraint(weakConstraint!) 
} 
assert(weakConstraint == nil) 

// New way of removing constraints: 

assert(weakConstraint == nil) 

autoreleasepool { 
    weakConstraint = view.widthAnchor.constraint(equalToConstant: 10) 
    weakConstraint!.isActive = true 
} 
assert(weakConstraint != nil) 

autoreleasepool { 
    weakConstraint!.isActive = false 
} 
assert(weakConstraint == nil)