快速打印锚定值

Question

如何打印出锚常数的值？例如：

let myButton = UIButton()
myButton.topAnchor.constraint(equalTo: view.topAnchor, constant: 5).isActive = true
myButton.bottomAnchor.constraint(equalTo: view.bottomAnchor).isActive = true
myButton.leadingAnchor.constraint(equalTo: view.leadingAnchor).isActive = true
myButton.trailingAnchor.constraint(equalTo: view.trailingAnchor).isActive = true
print(myButton.topAnchor.constant)//this would print 5

Answer 1

您错了这个概念。常数用于锚定的约束。锚不具有常量。 约束。因此，您需要做的是维护约束的引用并访问常量。

if (index < 3) return subTriangles[index];
return null;

一个视图只能有一个 let myButtonTopAnchorConstraint = myButton.topAnchor.constraint(equalTo: view.topAnchor, constant: 5) myButtonTopAnchorConstraint.isActive = true myButton.bottomAnchor.constraint(equalTo: view.bottomAnchor).isActive = true myButton.leadingAnchor.constraint(equalTo: view.leadingAnchor).isActive = true myButton.trailingAnchor.constraint(equalTo: view.trailingAnchor).isActive = true print(myButtonTopAnchorConstraint.constant) //Prints 5 ，但相对于该锚点可以有多个约束。