設置`constraint.isActive = false`是否解除約束？

Question

說我要刪除一個約束，傳統上，我會做：

view.removeConstraint(constraint) 

然而，現在有用於安裝/卸載限制新的isActive方法。

如果我做到以下幾點：

constraint.isActive = false 

將它從內存中正確刪除呢？

Answer 1

是，

constraint.isActive = false 

在做同樣的事情：

viewThatOwnsConstraint.removeConstraint(constraint) 

因此，如果持有到約束的唯一的事情就是看，那麼這將正確地從內存中刪除。

---

這裏的證明：

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)