如何将变量合并到 NSLayoutConstraint 字符串中?

How do you incorporate a variable in a NSLayoutConstraint string?

是否有如下演示的在约束字符串中使用变量的正确方法?

let x = 6
self.addConstraints(
    NSLayoutConstraint.constraintsWithVisualFormat(
    "H:|-x-[subView(==16)]|",
    options:[], metrics:nil,
    views:viewDictionary))

self.addConstraints(
    NSLayoutConstraint.constraintsWithVisualFormat(
    "V:|-x-[subView(==16)]|",
    options:[], metrics:nil,
    views:viewDictionary))

这就是 metrics 词典的用途。传递像 [ "x": x ].

这样的字典